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Revisiting the Five-Minute Rule

Soulskill posted more than 5 years ago | from the more-things-change dept.

Data Storage 153

In 1987, a study published by Jim Gray and Gianfranco Putzolu evaluated the trade-offs between holding data in memory and storing it on a disk. Known widely as the "five-minute rule," their research was updated and expanded 10 years later. Now, as jamie points out, Communications of the ACM is running an article by Goetz Graefe with another decennial update, evaluating the rule using hardware and software typical of 2007, with an eye toward how flash memory will affect the situation. An excerpt from Graefe's conclusion: "The 20-year-old five-minute rule for RAM and disks still holds, but for ever-larger disk pages. Moreover, it should be augmented by two new five-minute rules: one for small pages moving between RAM and flash memory and one for large pages moving between flash memory and traditional disks. For small pages moving between RAM and disk, Gray and Putzolu were amazingly accurate in predicting a five-hour break-even point two decades into the future. Research into flash memory and its place in system architectures is urgent and important. Within a few years, flash memory will be used to fill the gap between traditional RAM and traditional disk drives in many operating systems, file systems, and database systems."

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Five mins is too long.. (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#28586383)

..to achieve first post!

AFRICANS!! (-1, Troll)

Anonymous Coward | more than 5 years ago | (#28586539)

COONS niggers and JIGABOOS!! and dune coons and porch monkeys and watermelon and fried fuckin chicken! YEAH! dont forget thugs and gangstas and ebonics and crackrock and pimps and hos too!! hey what do you call a nigger with a stutter? a co-coon!

does this offend you?

for those wondering: (4, Informative)

wjh31 (1372867) | more than 5 years ago | (#28586385)

http://en.wikipedia.org/wiki/Five-minute_rule [wikipedia.org]

"The 5-minute random rule: cache randomly accessed disk pages that are re-used every 5 minutes."

Not to be confused with (5, Funny)

salahx (100975) | more than 5 years ago | (#28586403)

The more useful 5 second rule [wikipedia.org] .

Re:Not to be confused with (0, Offtopic)

ZosX (517789) | more than 5 years ago | (#28586463)

I adhere to the 30 second rule myself.... :)

Re: Not to be confused with (1)

megabulk3000 (305530) | more than 5 years ago | (#28587037)

Nor the funkier 3 minute rule [youtube.com] .

Re:Not to be confused with (3, Interesting)

johannesg (664142) | more than 5 years ago | (#28587705)

The more useful 5 second rule [wikipedia.org] .

That's just utterly disgusting. Do people in the US really believe that you can eat food that's fallen on the floor if you pick it up fast enough?

Re:Not to be confused with (3, Insightful)

SUB7IME (604466) | more than 5 years ago | (#28587925)

I know, right? What a disgusting waste of perfectly good food that has been on the ground for only 10 seconds!

Re:Not to be confused with (4, Funny)

michaelhood (667393) | more than 5 years ago | (#28587983)

I'd rather be a disgusting American than a naive European with no sense of humor..

Re:Not to be confused with (1)

akayani (1211810) | more than 5 years ago | (#28591151)

Obviously it depends on how clean the floor is.

I would be eating anything that fell on the floor in England! But Australians not only have clean floors but we shower at least once a day. ;)

Re:Not to be confused with (2, Funny)

jweller (926629) | more than 5 years ago | (#28588067)

No silly, but if you catch it on the bounce, it's like it never happened

Re:Not to be confused with (1)

Tubal-Cain (1289912) | more than 5 years ago | (#28588135)

Do people in the US really believe that you can eat food that's fallen on the floor if you pick it up fast enough?

Well, if you accept that my brother fits the definition of "person", and various snacks (pretzels, chips, hard candy (still wrapped)) as "food", then some people in the US don't restrict themselves to 5 seco^Wminu^W^da^Wmonths.

Though I am sure the attitude is not limited to the US.

Re:Not to be confused with (1)

jo42 (227475) | more than 5 years ago | (#28588159)

You need to watch the Mythbusters episode on the 5 second rule.

Re:Not to be confused with (2, Insightful)

Kaboom13 (235759) | more than 5 years ago | (#28589003)

Well the confusion is, unlike your dirt-floor huts full of your own feces, in real countries like America we have clean tile floors with miraculous inventions we call "mops".

Carpets are safer ... (3, Interesting)

tomhudson (43916) | more than 5 years ago | (#28589083)

Carpets don't transfer as many bacteria [nytimes.com]

Scientists have put the commonly-cited five-second rule to the test. They found that food that comes into contact with a tile or wood floor does pick up large amounts of bacteria. Food doesn't pick up many germs when it hits carpet, but it does pick up carpet fuzz.

Since this is slashdot, I'd bet most will pick bacteria over carpet fuzz any day ... after all, if it doesn't look fuzzy ...

or this ... [scienceline.org]

many people believe that gastric acid enzymes found in the stomach are strong enough to destroy the "small, harmless" amount of bacteria that could gather on a piece of food in five seconds. But are these bacteria really harmless?

In 2003, Jillian Clarke, then a high school senior, decided she wanted to find out. During an internship at the University of Illinois at Urbana-Champaign, she and a doctoral candidate, Meredith Agle, took swab samples from floors all over the campus, including labs, hallways, and bathrooms, and found that the amount of bacteria on the floors was very low. When she published her research, she concluded that if a piece of food falls on a relatively clean floor, the five-second rule is, in fact, applicable.

Re:Not to be confused with (2, Funny)

Millenniumman (924859) | more than 5 years ago | (#28591989)

Normal floors are probably safer than your hands. If it's in your own home and you just dropped it or something, I can't even really imagine why it would be mentally bothersome.

It's not really an issue if you have a dog, though.

Combined rule (1)

syousef (465911) | more than 5 years ago | (#28590955)

The lesser known 5 minutes 5 second rule combines the two: It states that if the case is left off a desktop computer for more than 5 minutes and 5 seconds Pizza and coke will spontaneously migrate from a computer lab desk and contaminate your RAM, CPU and motherboard.

Re:for those wondering: (-1, Offtopic)

Ant P. (974313) | more than 5 years ago | (#28586599)

What's with the fucking retard doing all these "offtopic" moderations lately?

Re:for those wondering: (1)

Hobyx (1175577) | more than 5 years ago | (#28587615)

Thanks.. it's odd that they didn't include that in the post.

Re:for those wondering: (1)

Twinbee (767046) | more than 5 years ago | (#28588413)

Will the 5 minute rule increase to 10 or even 20 when RAM becomes mega-cheap, and 64 bit OSs take off to take advantage of >4GB memory addressing?

Re:for those wondering: (1)

Korin43 (881732) | more than 5 years ago | (#28589021)

I really wish programs would just leave everything in memory and let the operating system page it out as it needs to. I have 4 Gb of memory and even with 'preload' set to prefetch everything, I'm still only using 1 Gb right now (it was around 200 Mb before I installed preload). And Ubuntu doesn't start swapping until it needs to, so no swap used.

I have a 5 minute rule with my girlfriend (-1, Troll)

Anonymous Coward | more than 5 years ago | (#28586395)

To be quite honest, it's an attempt to cover up my impotence.

Is this like the 5-second rule? (-1, Redundant)

Anonymous Coward | more than 5 years ago | (#28586407)

If you drop data on the floor you can re-use it as long as it wasn't on the floor more than 5 minutes?

Flash memory? (2, Insightful)

NitroWolf (72977) | more than 5 years ago | (#28586449)

I couldn't quite figure out if the article willfully ignored the advent of SSDs or was written before they were available and not updated to include them (but it appears the article was updated to include other current technology).

Given the fact that SSDs are likely going to replace rotational media for most applications in the future, it makes this article basically meaningless, at least insofar as the fact that flash memory and the disk are/will be synonymous. As the article is basically predicated around the entire fact that flash memory will change the 5 minute rule to a degree, it invalidates the entire article.

To be relevant, the article really needs to include the current state of SSDs and a likely projection (10 year) of where the state of the art in SSDs.

I do, however, suspect we may see a shift from drives all together at some point (perhaps more than 10 years, but perhaps not) and the computer will just have persistent storage for everything in MRAM or some other technology that obliterates the line between RAM (for speed) and drives (for storage) - it's just one big pool that's hyper fast and persistent.

So really, I don't think this article has held up in even the intervening two years since 2007, and it certainly won't hold up for another 10 years.

What article? (2, Insightful)

argent (18001) | more than 5 years ago | (#28586505)

The article I read spent a good deal of time talking about flash memory. What article are YOU referring to?

Re:What article? (0, Offtopic)

digitalaudiorock (1130835) | more than 5 years ago | (#28586533)

Wow...almost nothing but offtopic and redundant posts so far. As for me...I misread the title and assumed it was about eating a Cheeto that fell on the floor.

Re:What article? (0, Offtopic)

Smivs (1197859) | more than 5 years ago | (#28586781)

Wow...almost nothing but offtopic and redundant posts so far.

Well, this is /. What do you expect?

Re:What article? (1, Funny)

causality (777677) | more than 5 years ago | (#28586829)

Wow...almost nothing but offtopic and redundant posts so far.

Well, this is /. What do you expect?

Natalie Portman and hot grits.

Re:What article? (1)

orngjce223 (1505655) | more than 5 years ago | (#28587095)

Meh, in Soviet Russia, hot grits joke about you.

*shrug* You get what you pay for, and since I don't see any subscribers in this particular subthread...

Re:What article? (-1, Redundant)

Smivs (1197859) | more than 5 years ago | (#28587749)

Wow...almost nothing but offtopic and redundant posts so far.

Well, this is /. What do you expect?

I've just been modded 'Offtopic' for this </gobsmacked>.
Bet THIS post is 'Redundant' </cynicism>

Re:What article? (4, Insightful)

amorsen (7485) | more than 5 years ago | (#28586635)

The article I read spent a good deal of time talking about flash memory. What article are YOU referring to?

The article treats flash as something you place in between hard drives and memory. This turned out not to happen (with a few exceptions). SSD's simply replace hard drives. Hybrid systems are rare, and it doesn't look like they will become more common -- either you can live with the slowness of hard drives, or you can't. The mainstream will switch to SSD's for everything except backup applications.

There are some hybrid SAN's, but they're damn expensive. At that price they have a hard time competing with simpler pure-flash SAN's.

Re:What article? (1)

peragrin (659227) | more than 5 years ago | (#28586707)

The grandparent was talking about hybrids, but also something new. If and when MRAM becomes possible the technological hard drive wether spinning or flash is gone.

Indeed I am waiting for a true hybrid system to be built. One that has the OS installed in read only flash and applications on a separate drive. you might ask why? but then stop to realize what would happen if viruses couldn't overwrite the system settings. that to clean up a virus all you had to do was to reboot.

OS patches? (1)

tepples (727027) | more than 5 years ago | (#28586769)

I am waiting for a true hybrid system to be built. One that has the OS installed in read only flash and applications on a separate drive. you might ask why? but then stop to realize what would happen if viruses couldn't overwrite the system settings. that to clean up a virus all you had to do was to reboot.

How would such a hybrid system correct a discovered defect in the operating system?

Re:OS patches? (1)

vipw (228) | more than 5 years ago | (#28586863)

I propose a physical switch to toggle between read/write and read only. Even if it could be controlled remotely by a management server, it would provide a nice increase in security.

Re:OS patches? (2, Informative)

tepples (727027) | more than 5 years ago | (#28586935)

I propose a physical switch to toggle between read/write and read only.

And have social engineers disguise malware as OS updates or dancing bunnies [msdn.com] , prompting the home user who doesn't understand risks to flip the switch to see the dancing bunnies.

Re:OS patches? (1)

Jah-Wren Ryel (80510) | more than 5 years ago | (#28587541)

And have social engineers disguise malware as OS updates or dancing bunnies, prompting the home user who doesn't understand risks to flip the switch to see the dancing bunnies.

You can't make something 100% foolproof, the world will just invent a better fool. But you can make the lives of the non-fools better.

Re:OS patches? (0, Flamebait)

Runaway1956 (1322357) | more than 5 years ago | (#28588257)

MSDN? Noted. The author of that article has a vested interest in an operating system prone to such exploits. He makes use of chmod in Linux to make a point - but he fails to note that the Linux user is somewhat less likely to a: have admin rights or to b: grant admin rights to a program if he has them.

Dancing bunnies indeed. When I look at bunnies, I see food. (actually, they are catfood or dogfood more often than they find their way onto my table) I don't have any desire to see food dance.

Re:OS patches? (2, Interesting)

tepples (727027) | more than 5 years ago | (#28588351)

MSDN? Noted. The author of that article has a vested interest in an operating system prone to such exploits.

Ad hominem.

the Linux user is somewhat less likely to a: have admin rights or to b: grant admin rights to a program if he has them.

In the case of Linux on the home desktop, the owner of the PC has admin rights, and I don't see how granting setuid is any harder to social-engineer out of an inexperienced Linux user than out of an inexperienced Windows user.

When I look at bunnies, I see food.

What about dancing scantily clad people of the appropriate sex?

Re:OS patches? (1)

Runaway1956 (1322357) | more than 5 years ago | (#28588547)

Errr - realize that a number of people migrate to Linux because they believe Linux to be more secure than Windows. Such people are more likely to do some studying, and follow best practices as they learn them. I'll even go so far as to say that people migrating to Linux tend to be more security minded when they need or want to use a Windows machine.

In the end, I'll trust an inexperienced Linux user just a little bit further than I'll trust that "average" Windows user. At least our inexperienced Linux user has the psychological ability to say "I screwed things up, didn't I?" rather than saying "This computer SUCKS - it won't do what I want it to do!"

As for dancing nekkid women - they beat my door down to dance for me. There isn't time to follow links to look at more. ;)

Re:OS patches? (1, Insightful)

Anonymous Coward | more than 5 years ago | (#28590695)

1. If what you say is true, then you are essentially arguing that a typical Linux user is better than a typical Windows user not because of technological advantages in Linux, but because of a social quirk. In essence, you just ceded the point you were arguing against: social engineering is a hole that no amount of technological boundaries can ever stop.

2. That said, I know a lot of people who switch to Linux, or to Mac, or to Firefox, or to some other miracle-pill software because they've heard it's more secure, and then they feel they don't have to take any real precautions or worse, they stop using the precautions they had been using. I'm not at all convinced that a user who migrates because they've heard Linux is secure is more savvy to social engineering in general.

That said, I agree that the average Linux user is probably more likely to think about security, using similar reasoning (but not quite the same). I think the OS/religious metaphor works really well here:

1. People who think for themselves are more likely to change OS, for any reason of their own.
2. More people started with Windows than any other OS.
3. Thinking for yourself is a trait assumed to be equally likely in people who started with Windows as in any other OS.
4. Therefore, all things being equal, people who think for themselves will leave Windows for an alternative, leaving a disproportionate number of people who don't think for themselves with Windows. Even if Windows does not make people fail to think for themselves.

For real fun, you can replace "Windows" with "Christianity" and I think the same basic argument holds up, leading to a migration of intelligent, independent thinkers to atheism which does not actually indicate that atheism causes better thinking. I think atheism is probably right, myself. Just sayin'.

Re:OS patches? (1)

neomunk (913773) | more than 5 years ago | (#28586921)

Presumably by the tech flipping a hardware rw/ro switch on the drive after proper isolation conditions are met.

Yes it's a pain, but much like dentistry it's a preventative pain that spreads a small controlled annoyance over a planned schedule as opposed to a big problem cropping up all at once unexpectedly (and usually at the worst possible time).

Re:OS patches? (1)

tepples (727027) | more than 5 years ago | (#28586997)

Presumably by the tech flipping a hardware rw/ro switch on the drive after proper isolation conditions are met.

If such a system were deployed in home PCs, how much would it cost for the tech to visit each user and flip the switch? I see no way to make such on-site service cost-effective.

Re:What article? (1)

maxume (22995) | more than 5 years ago | (#28586783)

What about my data? I guess for the ecosystem hardened system storage is a nice improvement, but for users, it only fixes 1/2 of the problem.

Re:What article? (1)

orange47 (1519059) | more than 5 years ago | (#28587123)

SSD's simply replace hard drives.

no they don't, show me SSD that can replace 1Tb HDD.

Re:What article? (1)

amorsen (7485) | more than 5 years ago | (#28587327)

What's the problem? If you need to store 1TB and you can live with the slowness of hard drives, you use hard drives. If you can't, you use SSD's -- or possibly an array of small fast hard drives, but SSD's will most often be cheaper.

What you don't do is build a hybrid system with automatic page migration between SSD and hard drives -- and that is what the article assumes will be commonly used. Hierarchial storage has a very small niche, and SSD's won't make it more popular.

Hence the article is useless.

Re:What article? (1)

Jeff DeMaagd (2015) | more than 5 years ago | (#28588335)

Inexpensive SSDs tend to be pretty slow, defeating the point of going SSD.

Re:What article? (1)

Miseph (979059) | more than 5 years ago | (#28587365)

Wait a year and a half, it'll be here.

How is that even Slashdotters seem to forget nothing in computing is static, that any arbitrary amount of storage or memory or speed will inevitably come to exist? It was only a few years ago that 1tb HDDs were an object of speculation themselves, SSDs will get there soon enough.

Re:What article? (1)

DJRumpy (1345787) | more than 5 years ago | (#28587443)

Yes but they are still prohibitively expensive for most typical end users. I'm actually a little surprised that they remain so expensive given that they've been around a few years and that the capacity on them is gaining so quickly. Considering how cheap storage is these days I have to wonder if it's a technical reason that they remain so expensive, or if they simply haven't hit that sweet spot of (Cost x MB).

In any case, they need to hurry the hell up. Papa needs a new pair of dimms...

ZFS (2, Interesting)

Anonymous Coward | more than 5 years ago | (#28587239)

The article I read spent a good deal of time talking about flash memory. What article are YOU referring to?

The article treats flash as something you place in between hard drives and memory. This turned out not to happen (with a few exceptions). SSD's simply replace hard drives. Hybrid systems are rare, and it doesn't look like they will become more common -- either you can live with the slowness of hard drives, or you can't. The mainstream will switch to SSD's for everything except backup applications.

There are some hybrid SAN's, but they're damn expensive. At that price they have a hard time competing with simpler pure-flash SAN's.

Except if you're using ZFS. You can put a (SLC or MLC) SSD drive into just about any system and tell it to act as a (write or read) cache.

Re:What article? (2, Insightful)

a-zA-Z0-9$_.+!*'(),x (1468865) | more than 5 years ago | (#28587391)

Flash is still 10-20x the price for the same GB. Recent developments have increased max magnetic density 1000x current. While you may be happy with 128GB, think of what you could do with 128TB. Store all your HD movies, lectures, conversations, life. Keep all your web history, including pix and html. And then there's the "killer app" we haven't reached yet...

tOM

Re:What article? (0)

Anonymous Coward | more than 5 years ago | (#28587513)

"Keep all your web history, including pix and html."

You may not want that yourself, but your government may love the possibility of requiring that...

Re:What article? (1)

Jah-Wren Ryel (80510) | more than 5 years ago | (#28587519)

There are some hybrid SAN's, but they're damn expensive. At that price they have a hard time competing with simpler pure-flash SAN's.

FWIW, Sun's ZFS has the ability to automagically use flash drives as intermediate stage in front of rotating disks.

Re:What article? (1)

bwcbwc (601780) | more than 5 years ago | (#28587607)

The other problem with the role ascribed to flash memory in the article is the write-wearing of flash. If flash memory decays with fewer writes than disk memory, there's a trade-off between the overall lifetime of the disk subsystem and the use of flash memory for caching/buffering. If you do most of your active writes to flash as a buffer before doing sector-based writes to magnetic disk, sure your performance is better, but you shorten the lifetime of the disk subsystem.

A more likely scenario is to have an SRAM or DRAM cache buffering the Flash memory and use a combination of flash and magnetic disk for secondary storage. Magnetic disks would also serve as offline storage.

Another impact of the continuing miniaturization of CPU features is going to be some truly humongous on-board L2 and L3 caches. I figure 6-8 cores on a single die is probably the most that is practical for connecting to a 64-bit memory and I/O system so after that point you have to start integrating more motherboard features onto the CPU die, or go to a 128-bit data bus. Eventually we may do away with system RAM completely and just have multi-gig memory modules on CPU, using flash drives as secondary storage.

Re:What article? (4, Informative)

wwwillem (253720) | more than 5 years ago | (#28588201)

Hybrid systems are rare, and it doesn't look like they will become more common.

You're probably right when we talk about desktop PCs and laptops. I'm sure the latter will be SSD only in 5-10 years time, and desktops are also losing terrain quickly against laptops.

But when we look at datacenter grade enterprise storage, hybrid systems are currently picking up fast. The advantage is that because of the fast 'flash memory cache' you can use SATA disks instead of the FC/SCSI drives, where the former are both much bigger and much cheaper. Instead of 300 146GB 15K FC disks, you only need 30 1.5 TB 7200 RPM SATA disks. For the same capacity this results in much lower power bills, less DC floor-space costs and much better performance.

If you say "There are some hybrid SAN's, but they're damn expensive.", have a look at what [shameless plug-on] Sun is doing [sun.com] , and yes, I work for Sun [plug-off]. But other storage vendors (NetApps, EMC, IBM, etc.) are starting to do similar things.

So the whole "storage-stack" gets more and more hybrid and integrated. It consists of the full gamut of DRAM, flash memory, hard drives and finally tape. Each of these have their own strength and are used best in combination.

Re:What article? (1, Interesting)

Anonymous Coward | more than 5 years ago | (#28588241)

Flash replacing spinning drives is something I've heard of for a few years now, but it turns out to have not happened yet. Instead, it overlaps optical and magnetic drives due to price and capacity issues. It's obliterated all other temporary portable storage (floppies, cd-rw, dvd-rw), but it doesn't compete with the big reusable media on storage-per-dollar (hard drives are an order of magnitude cheaper) and it doesn't compete with long term cheap write-only storage (blank DVDs are still an order of magnitude cheaper in their common form... $.35 or so per blank single sided disc that holds 4 gig, vs $5-$15 for a 4 gig USB flash stick. And in newer tech, $15 will get you 50 gig of blu-ray). So for that kind of thing, flash isn't going to overtake magnetic storage for a long while yet, unless either flash gets a huge tech boost above and beyond its current rate of improvement, or hard drives hit a wall.

But the more expensive flash can slot right into the memory hierarchy, because its capacity and speed and price (and power draw?) fit right in between main memory and hard drives. The stuff that'd be silly for most hard drive use - $200 for a measly 32 gig of high performance flash - is still much cheaper than the equivalent capacity RAM, but much faster than the equivalent capacity of magnetic hard drive. While this may not be needed much in current desktops - we don't really need 32 gig of extra cache yet for our web browsers - it could certainly be immediately useful in servers. Discs are horrifically slower than RAM, after all.

AFAIK, they're already fooling around with using flash caches in databases.

Re:What article? (1)

DrDitto (962751) | more than 5 years ago | (#28589363)

Ya...if you run a 5-petabyte storage system, let me know if you replace all of that with flash. Heck, anybody who stores > 1 TB will be using disk drives (and that is a lot of people given video, 16-megapixel cameras, etc.).

No Common Hybrids? What about ReadyBoost and ZFS? (1)

spaceturtle (687994) | more than 5 years ago | (#28591717)

Isn't ReadyBoost [wikipedia.org] essentially a hybrid system?

Also I rememeber that one of the main disadvantages of Btrfs over ZFS was that I doesn't support using SSD to speed up overall access, while ZFS does [sun.com] .

Readyboost is just to get over low memory limits (1)

dbIII (701233) | more than 5 years ago | (#28591865)

Readyboost and Superfetch are really just hacks to get around the 3GB or so ceiling in 32 bit Vista due to incomplete support of the Pentium Pro and later processors (PAE extension). With the 64 bit versions (or the server 32 bit versions, or any OS produced by anyone other than Microsoft in the last decade) you can use real memory instead for improved performance. Consider that you are grabbing all that stuff from disk and doing the relatively slow write to flash to save time when it needs to go into memory later. The far better answer is to have enough memory and only handle the stuff once.

Re:Flash memory? (1)

NitroWolf (72977) | more than 5 years ago | (#28586579)

I'm somewhat curious as to why people would moderate the original post off topic? It's specifically addresses the article and is ABOUT the article. How is it off topic?

Given the fact that every other post in the article is modded offtopic, I suspect someone has gone through and just modded everything off topic.

Either way, the point still stands. The article fails to recognize or address SSDs in any way, shape or form. As such, the article is basically mostly irrelevant in 2009 and going forward. It's interesting to see show how technology has changed in a mere two years between when the article was written and now, but as a useful prediction tool, it's been completely obliterated by the SSD future. As my original post pointed out as well, the convergence of persistent storage and temporary storage will further invalidate the article.

As for the post by Argent, I wasn't sure if that was addressed to me or not - if so, I have no idea what you're talking about. Your post has absolutely nothing to do to with my original response.

Re:Flash memory? (1)

mac1235 (962716) | more than 5 years ago | (#28586639)

SSDs = Flash

Re:Flash memory? (1)

NitroWolf (72977) | more than 5 years ago | (#28586683)

No shit, that is exactly my point.

SSDs are set to replace rotational media. That was what I stated.
So... to make it more clear to the people with reading comprehension issues:

Flash memory is set to replace rotational media.

This article indicates that Flash Memory (AKA SSDs) are only going to be an intermediary between rotational media and RAM. This is clearly not going to be the case going forward... this is WHY I wrote the GP post and pointed out that it's invalid.

WTF. Seriously. Are people that incapable of reading what I wrote or is it really that unclear? Going back over what I wrote, it still seems pretty clear, but maybe not.

Re:Flash memory? (0)

Anonymous Coward | more than 5 years ago | (#28586767)

This article indicates that Flash Memory (AKA SSDs)

Nice back-pedaling there:

I couldn't quite figure out if the article willfully ignored the advent of SSDs

The article fails to recognize or address SSDs in any way, shape or form

Your main point seems to be:

Given the fact that SSDs are likely going to replace rotational media for most applications in the future

That's not a given. Like the article, I also believe that flash memory will be an intermediate between rotational media and RAM (maybe not for netbooks, but for servers and such). Since you believe the opposite, work on proving your claim instead of writing 2 pages that assume it.

Re:Flash memory? (2, Interesting)

Rockoon (1252108) | more than 5 years ago | (#28587117)

You ask for evidence. How about some evidence that SSD's are being used anywhere in the way that you describe.. as a cache between rotational media and ram.

There are millions of people already using SSD's as (superior) drive replacements.

Do you really want evidence of the fact that SSD's are already replacing drives, that many millions of them have been sold specifically for that purpose, that even companies like Apple offer SSD's as alternatives solutions to rotational media in their standard packages?

External hard drives == memory hierarchy (2, Insightful)

tepples (727027) | more than 5 years ago | (#28586801)

This article indicates that Flash Memory (AKA SSDs) are only going to be an intermediary between rotational media and RAM.

If your handheld device or subnotebook PC has only an internal SSD and no internal hard drive, then you will store any data that doesn't fit on your SSD on a hard drive plugged into a Hi-Speed USB port, copying it to the SSD when it is needed. For example, you'd keep the video footage that you are editing on the SSD and other projects on the hard drive. That sounds to me like a memory hierarchy, albeit one that occasionally requires manual intervention to connect the (offline) long-term mass storage to the machine.

Re:Flash memory? (1)

TheRaven64 (641858) | more than 5 years ago | (#28586831)

I think you need to RTFA again. It talks about flash being between RAM and rotational media in terms of performance characteristics not in terms of physical connections.

the king is dead (2, Interesting)

epine (68316) | more than 5 years ago | (#28588751)

What I love about slashdot is its scalability. The discussion ranges anywhere from the design of a Google data center in 2015 to some guy's psychological stance toward his next netbook purchase in 2009. Sometimes it's unclear which end of the spectrum is under debate, but the discussion happily progresses in a state of astral superposition. When this gets too confusing, even for slashdot, the moderation system helps to sort things out. For example, if the comment

Flash memory is set to replace rotational media.

is moderated +1 insightful, then we know we're talking about some guy's future netbook purchase. Or if the same comment is moderated -1 troll, then we know we're talking about Google data centers in 2015.

Flash memory begins to fade - ZDNet.co.uk [zdnet.co.uk] from 2005

"The scaling laws are not favourable to flash," said Tom Lee, an associate professor of electrical engineering at Stanford University and a founder of Matrix Semiconductor, which makes a 3D memory chip that performs flash-like functions. "The noises are getting louder now, so it looks like manufacturers are already in that new age of diminished gains."

Numonyx Breakthrough Delivers First 45nm NOR Flash Memory Chips [benchmarkreviews.com] from Jan 2009

"Numonyx engineers overcame major scaling limitations by developing new process techniques to produce the 7th generation MLC NOR flash on the industry's most advanced 45nm technology, and to be the first to bring the cost and performance benefits to our customers."
...
"At a time when the entire industry grapples with the scalability of all flash memory technologies, ..."

Brewster Kahle [ted.com]

I think Brewster Kahle is going to jump off a bridge when he learns that Seagate is exiting the disk drive business in 2010. If you think CERN or EOS cost a lot of money, try updating the budget with SSD specified as the primary storage layer.

A useful way to view this transition is the long tail on steroids. 99% of the world's stored information will be held by a few hundred mega-scale institutions (NASA, Google, CERN, GenBank) on rotating hard drives, while 99% of the world's gadgets have no hard drive at all.

The same thing happened in software. The C language represents a tiny sliver of source code written over the last ten years, but if you could measure the number of machine instructions executed by language of origin, C would continue to represent a very large slice of the pie. A major factor in the success of scripting languages is that the problems these languages don't handle well can be off-loaded to a well established compiled language. If you cherry pick your niche, it's amazing how much more convenient it looks compared to the ancestral technology which didn't.

I thought the paper was quite good, and more relevant than 99% of what I read these days. I'm always interested in analysis of hybrid solutions. In the engineering world, there is a de facto allergy to hybrid solutions. We tend to achieve the best result by scaling a single virtue to the max, rather than engaging in the jello-like trade-offs involved in balancing complementary virtues. I first began to think about this when ethernet trounced ATM by the simple measure of vastly over-provisioning bandwidth.

The exception to this is on the large scale where operational costs exceed all other costs, such as major data centers.

This is one of the reasons why progress in ecology is so painfully achieved: ecological systems almost always demand hybrid solutions, and we're not terribly comfortable with this. Engineers prefer monarchy. In ecological systems, life is complicated, and you can't just sit there and declare "A is set to trounce B".

Slashdot itself might have to fold when bio-engineering becomes the norm. It's pretty much impossible to make an insightful comment about a biological system. The moderation system will fall into disuse, and it will be pretty much anyone's guess what the OP actually meant.

Re:Flash memory? (2, Informative)

jelle (14827) | more than 5 years ago | (#28587531)

Flash is an SSD, but not every SSD is flash...

Re:Flash memory? (1)

jelle (14827) | more than 5 years ago | (#28587549)

Oh, and not all flash is an ssd either... (e.g. the BIOS chip)

So, actually: SSD != Flash...

Re:Flash memory? (0)

Anonymous Coward | more than 5 years ago | (#28587649)

What moving parts does a BIOS have?

Re:Flash memory? (1)

Jeff DeMaagd (2015) | more than 5 years ago | (#28588419)

The reason not all flash is an ssd, because in some cases, it's just a chunk rectangular storage. The BIOS isn't necessarily in a file system, nor does it typically have a special drive-like controller or unusual interface circuitry, it's a bare flash chip. Lots of microcontrollers have flash but don't have anything like a drive controller in them, it's just a different type of memory.

Re:Flash memory? (0)

Anonymous Coward | more than 5 years ago | (#28586679)

A SSD is just flash memory in a box that obeys a disk-like interface.

Re:Flash memory? (3, Informative)

Courageous (228506) | more than 5 years ago | (#28586987)

I couldn't quite figure out if the article willfully ignored the advent of SSDs or was written before they were available... As for the post by Argent, I wasn't sure if that was addressed to me or not - if so, I have no idea what you're talking about. Your post has absolutely nothing to do to with my original response.
 
Argent's post refers to "flash memory". You said the article ignored SSD's, however it did not. "Flash memory" is the technology that SSD's are composed of. Did you not know this? "Flash memory" is all over the article.


Flash SSD's will not replace SATA drives anytime within the next 4-6 years. In technology time, that's such long period of time, it would be quite difficult to make a credible projection for the consumer market space. For servers, where the segment is dominated by 10K/15K drives, you can expect flip over within 18 months.


C//

Re:Flash memory? (1)

NoOneInParticular (221808) | more than 5 years ago | (#28588331)

Why would SSD's not take over within the next few years? I expect that in one, two years time, all new notebooks will be flash based. Desktops will soon follow, possibly with a few year of a HDD next to the SSD for mass storage.

I for one do not need a 350 GB HDD on my notebook such as I have now. I would love to have better power life and snappier response though. 80GB is comfy for me, and has been so for 5 years. Movies and stuff I put on an external drive, and transfer when I need it. Netbooks already don't have HDDs. Why would you want to have a desktop that's 100% HDD based? Yes, to store your stash of pron and movies, a few TB HDD would be useful, but using it to also host your OS and user files and see your friends mock your system for its slowness? Why?

SSD beat HDD on speed, energy used and on longevity. All HDD has going for it is bytes per buck. Note that the computer race in the eyes of the consumer has always been on speed, never on storage.

Re:Flash memory? (2, Insightful)

Courageous (228506) | more than 5 years ago | (#28590199)

Depends what segment you're talking about. There isn't one market for HDD's, there are many. In both the enterprise archival and consumer mass storage segments, drives are sold pretty much $/TB. In that segment, you won't see significant penetration for 4-6 years. In other segments, sooner. I agree with you: I want a flash SSD for my laptop currently; it just hasn't quite yet reached the right price point. It will soon. And you're right: it's not $/GB that will be the deciding factor there.

There's also no reason to assume one way or the other. For example, I expect to put BOTH flash SSD and SATA into my desktop system shortly. I will continue to use the SATA for archival. I'll use the flash SSD as a working set.

Do you have 15K 2.5" drives in your workstation already? I have 15K 3.5" drives for my working set.

However, if you're like me, you must know that you are most unusual. It's a niche, surely, but hardly the mass market.

C//

Re:Flash memory? (2, Insightful)

Eskarel (565631) | more than 5 years ago | (#28591427)

If you've still got an external(or internal) physical HDD, then SSD's have not taken over. They've become a part of a new solution, not replaced an old solution.

Re:Flash memory? (1)

smaddox (928261) | more than 5 years ago | (#28587227)

I'm not sure that is entirely true. High capacity SSDs will need to write large chunks to have good write speeds, and to reduce wear. Having a separate small chunk cache will still be necessary.

Re:Flash memory? (1, Insightful)

m.dillon (147925) | more than 5 years ago | (#28587547)

SSDs are not likely to replace traditional hard drives any time soon, if ever. The cost differential is simply too high. While it is true that SSDs can effectively replace HDs on systems which do not require large amounts of storage (say, 64G-256G), the fact of the matter is that a 256G SSD is still three times as expensive as a 2TB hard drive. That is a 24:1 cost factor.

At the same time SSDs are becoming capable of replacing systems which do not have large storage requirements, HDs are becoming far more capable in systems which DO have large storage requirements, and driven by high resolution digital camera and video media consumer trends are clearly heading towards the larger storage requirement end of the spectrum.

-Matt

I'm still not clear on this.... (0, Offtopic)

ZosX (517789) | more than 5 years ago | (#28586499)

Isn't it still the case the flash drive speed slowly degrades as they fill up and delete blocks, as it marks blocks off as used even though they are half full, etc? And that windows 7 is going to somewhat address this issue? Also, are their claims now that you can get millions of writes still holding water? I'm not real convinced yet. The speed is there, but there still seem to be fundamental issues. Like for instance, this PC I'm using right now is a backup machine, and its old 40gig drive is really slow. I can boot linux off a USB flash drive. Would that be any faster, and more importantly, how long would the usb drive last from swapping? Theoretically it should be faster and throughput should be higher with USB 2. I'd only need like a 16 gig stick or something......

Re:I'm still not clear on this.... (0, Offtopic)

Lemming Mark (849014) | more than 5 years ago | (#28586587)

Guess it might be faster for some stuff but I'm guessing it'd probably be slower overall. USB flash sticks are quite different animals to the SSDs you get as hard drive replacements. Although they're both based on flash memory tech, AFAIK SSDs typically provide much higher performance (and because they're not running over USB you may also find they have lower CPU usage in operation and may reach higher bandwidths in practice).

If you want to make your existing machine fast you could install something like Puppy Linux, which IIRC runs itself entirely out of a ramdisk. You can boot that off CD-R / CD-RW or a USB stick and it'll run straight out of RAM the whole time, then save any configuration changes back to the CD-R / CD-RW / Flash stick when you shut down. It's small, wicked fast, includes Firefox. When my main PC's hard drive died I simply stuck a Puppy CD in the drive and used that for browsing, e-mail, etc until the replacement arrived.

Re:I'm still not clear on this.... (1)

Lemming Mark (849014) | more than 5 years ago | (#28586623)

Obviously, the problem with running Puppy in a ramdisk and not having it write back until shutdown is that if it crashes you'll lose your data. You can maybe do a full install to avoid that, I'm not sure ... it'd be nice if it could persist data to storage on request but I don't know if it can.

Re:I'm still not clear on this.... (1)

ciderVisor (1318765) | more than 5 years ago | (#28586969)

It's small, wicked fast, includes Firefox.

To be pedantic, it's the Mozilla SeaMonkey suite. Puppy's a great distro though, especially for older machines.

Re:I'm still not clear on this.... (1)

Lemming Mark (849014) | more than 5 years ago | (#28587059)

It's small, wicked fast, includes Firefox.

To be pedantic, it's the Mozilla SeaMonkey suite. Puppy's a great distro though, especially for older machines.

Hrmmm, OK! I imagine using a combined suite makes sense, space-wise, perhaps? I always liked using SeaMonkey, before the days of Firefox, so that's cool.

I *think* the version I actually used did have Firefox but that was a very long time ago now. When I used it I'm not sure if they had a package manager, even!

I should really burn a new Puppy CD so that I'm prepared when this computer dies ;-) Or, given the speed of the device isn't an issue if running from a ramdisk, I could buy a dirt cheap 512MB USB stick and have several hundred megs free for my own files!

Re:I'm still not clear on this.... (1)

ZosX (517789) | more than 5 years ago | (#28586629)

So I RTFA to see if it answered any of my questions and it seems that they are just saying that they don't have the answers either. I don't know if I agree with their use of flash as extended ram. Why not just make it a super fast drive that sits close to the cpu and give it the illusion of being an IDE drive so us normal users can just make it a swap partition. Oh, and give the chip a socket so we can upgrade/replace it later. I don't think it would cost manufacturers a great deal more to add one more socket, but it might cost a bit more as its hard to find cheap motherboards with say more than one PCIex16 slot or more than 2 DIMM connectors. Or maybe it is that they want you to spend the extra $20 for such features......

Erase traffic burns up SSDs (1)

tepples (727027) | more than 5 years ago | (#28586821)

I don't know if I agree with their use of flash as extended ram. Why not just make it a super fast drive that sits close to the cpu and give it the illusion of being an IDE drive so us normal users can just make it a swap partition.

A swap partition has a lot more erase traffic than a data partition, and access patterns high in erases are thought to wear out SSDs faster than hard drives.

Re:Erase traffic burns up SSDs (1)

ZosX (517789) | more than 5 years ago | (#28586861)

Does swap really erase? I was always just under the impression that if a block was no longer used it was just demapped. If the OS decides to write to that block again it just merely overwrites that block. Unless I'm missing something here? I thought the problem with running swap on a flash was the sheer number of writes involved, not the erases. The problem with erasing, from what I can tell, is when you have a temp folder that keeps erasing and further reducing the number of free whole blocks by fragmenting them with new files....

rarely-rewritten logical sectors (1)

tepples (727027) | more than 5 years ago | (#28586891)

Does swap really erase? I was always just under the impression that if a block was no longer used it was just demapped. If the OS decides to write to that block again it just merely overwrites that block.

A flash block must be erased before it is overwritten, and each sector is guaranteed for only about 100,000 erases. Lots of writes are fine on larger SSDs because the wear leveling program in the drive's controller will move rarely-rewritten logical sectors (such as free space and read-only files) to more-worn physical sectors. But if you're devoting an entire device to swap, there won't be a lot of rarely-rewritten logical sectors for the controller to make use of.

Re:rarely-rewritten logical sectors (1)

TheRaven64 (641858) | more than 5 years ago | (#28586995)

But if you're devoting an entire device to swap, there won't be a lot of rarely-rewritten logical sectors for the controller to make use of.

Only if you have a very unusual swap load, where the swap space is 100% full and every swap operation is exactly that; an exchange of some pages between memory and disk. In practice, a swap partition is likely to be largely full of data that isn't ever accessed. For example, if an app leaks some memory, this will be swapped out after not being used for a while and never swapped back in. If an application spends most of its time idle, it will be swapped out and stay on disk for a long time, being occasionally swapped back in to do something and then swapped out (which only involves writing the modified pages) again after it becomes idle.

I thought you were referring to the 5 second rule (3, Funny)

vaporland (713337) | more than 5 years ago | (#28586531)

five minutes is an awful long time for food to remain on the floor before you pick it up to eat it...

Re:I thought you were referring to the 5 second ru (1)

maxume (22995) | more than 5 years ago | (#28586549)

How clean is the floor and how sticky is the food?

Stickier food may be better to eat off of the floor, as the part that touched the floor is somewhat more likely to stick to the floor, rather than some of the floor sticking to the food that you eat.

Re:I thought you were referring to the 5 second ru (1)

that IT girl (864406) | more than 5 years ago | (#28586687)

Aha, finally someone else who gets this concept. I have tried (and failed, so far) to explain this to a few people.

Re:I thought you were referring to the 5 second ru (1)

John Hasler (414242) | more than 5 years ago | (#28586557)

Not as long as you scrape all the dog hair off first.

Re:I thought you were referring to the 5 second ru (1)

redKrane (672370) | more than 5 years ago | (#28586583)

Fucking same thing for me haha. I thought they were going to show evidence that the food one drops on the floor is in fact *not* safe within 5 minutes, only within 2.

Re:I thought you were referring to the 5 second ru (1)

Opportunist (166417) | more than 5 years ago | (#28586813)

It's just a bit dirty, it's still good, it's still good!

Re:I thought you were referring to the 5 second ru (1)

TheRaven64 (641858) | more than 5 years ago | (#28586841)

If you'd RTFA in the last article about the 5-second rule, then you'd know that it is a modern formulation of Genghis Khan's 12-hour rule, stating that you should not eat meat that had been on the floor for more than 12 hours. You'd also have learned that the amount of bacteria transmitted from a floor in five second and five minutes is about the same.

Numbers all over the place (0)

Anonymous Coward | more than 5 years ago | (#28586561)

Started reading and found stuff like "every 400 seconds, which they rounded to five minutes" - 5 minutes = 300 seconds, so their rounding was knock 33% off - great accuracy.

Then "The break-even interval is about inversely proportional to the record size. ... and two minutes for 4KB pages." followed by "Nonetheless, the breakeven interval for 4KB pages was still around five minutes." - so was 2 minutes - now 5 minutes so a 150% increase is ignored.

Glad these people don't work out my utility bills.

Do the old premises still apply? (1)

FranTaylor (164577) | more than 5 years ago | (#28586717)

These days, the database is not what it used to be. Local clients use shared memory. JVMs and entire web servers are incorporated directly into the database executables. The old concept of the separation of the database from its clients no longer applies.

When you are running a database, what business does the OS have, deciding what data is to be paged in or not? The database is in a far better position to make these decisions, and it can be based on much better rules than "5-minute" heuristics.

Extending the memory cache abstraction to paging (1)

m.dillon (147925) | more than 5 years ago | (#28587319)

The way I see it, the advent of SSD storage gives us the ability to extend the cache layering abstraction we already use into a smooth continuum between the cpu's L1 cache (L2, L3, dram simms, etc...) and traditional HD-based disk cache. SDD doesn't quite close the gap but it actually fills a major portion of it.

The article makes the mistake of assuming fairly small SSDs, but is otherwise spot-on. It isn't possible to use tiny SSDs in the 8G range as a paging medium for caching memory, it simply isn't enough storage for wear levels to be acceptable. On the other-hand, a 64G-256G SSD provides a better basis both in wear leveling and in traditional cache metrics. This is particularly true as hard drives exceed the 2TB/unit mark.

There is a general fallacy here where some people seem to believe that SSDs will replace hard drives. That is not going to happen any time soon or possibly even ever, not unless flash densities can be increased by two orders of magnitude. The cost per byte of storage is immense between the two. What *IS* happening is that SSDs are now capable of replacing HDs in particular circumstances where the absolute quantity of storage is not the primary need. At the same time traditional HDs themselves have replaced a large portion of the spectrum that used to be held by archival media, and the need for terrabyte-sized storage systems has increased drastically as high resolution digital cameras and video become more important to the general consumer.

I think most people still have the 'paging is bad' mindset, because traditional paging is a fairly inefficient operation on a traditional hard drive. That isn't the case when it comes to SSDs as the technology matures. Paging, in fact, could become the tour-De-force that allows systems to more fully utilize all of their resources. SSDs have not quite gotten to this point yet but it is obvious that they will quickly get there, probably in as little as two years.

-Matt

Re:Extending the memory cache abstraction to pagin (1)

The_Wilschon (782534) | more than 5 years ago | (#28588115)

I expect that SSDs will in fact replace HDDs. But probably not with FLASH. Other solid state non-volatile random access memory technologies are likely to come around, hopefully with better wear and density characteristics. <tongue-in-cheek>There is a general fallacy here where some people seem to believe that SSDs can only ever be composed of FLASH</tongue-in-cheek>

Re:Extending the memory cache abstraction to pagin (1)

Eskarel (565631) | more than 5 years ago | (#28591631)

I'm not sure where people get this acceptable wear levels for SSD's thing.

All the math I've seen indicates that, presuming reasonable wear algorithms, if you write the volume of your data to disk every day your drive will last for about 30 years and that it will scale linearly with shifts up or down in that amount. An ordinary hard disk lasts about 5 years, so for your 8 GB disk you'd have to be writing approximately 48 GB of data to it every single day in order for it to not last longer than a current HD, and the SSD is still readable at the end(though this isn't super important for caching). That's certainly not an implausible amount of data, even for a home desktop user, but it is fairly high, and since it's fairly linear, you'd reach a feasible number for pretty much any ordinary data set well before 64 GB, let alone 256 GB

I think that it's probably also inaccurate to say that SSD's will never replace HDD's. Hard drive sizes are certainly increasing, but the need for capacity isn't increasing anywhere near as fast. Under present usage patterns, most users will never fill a 1 TB drive within the lifetime of the drive, certainly not with anything that can't be archived. If you can get price point down to 25 cents per GB it would probably be worthwhile to use them in pretty much any circumstance excluding applications involving really heavy writes or a lot of long linear reads. Data Center Storage is already substantially more expensive than that, and the extra speed would make up for a lot of space issues. Even if you had to use 4 disks instead of 1.

That price point probably won't be met in the next year or so, but it's certainly achievable within the next couple. True by then HDD's may be 4 TB for the same price or more, but a couple of TB you don't need vs a faster system isn't much of a choice.

The new rule...Cache Everything.... (0)

Anonymous Coward | more than 5 years ago | (#28590911)

....don't make slow ass websites. Cache everything. That is the new rule. Google does it. Facebook does it.

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