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How Does Flash Media Fail?

kdawson posted more than 5 years ago | from the in-the-pan dept.

Data Storage 357

bhodge writes "Aside from the obvious 'it stops working' answer, how does flash media — such as USB, SD, and CF — fail? Unlike with traditional hard drive, where anyone who's worked with computers for a while knows what a drive failure looks like, I don't know anyone who has experienced such a failure with flash. I've haven't been able to find more than scant evidence of what such failures look like at the OS level. The one account I have found detailed using a small USB drive for /var/log storage; it failed very quickly, and then utterly (0 byte unformatted device), after five years of service in the role. This runs contrary to other anecdotal claims that you should still be able to read the media after you can no longer write to it. So my question is: what have you seen of the nature of flash media failure, if anything?"

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It Elects a Nigger President (-1, Troll)

Anonymous Coward | more than 5 years ago | (#27530959)

Niggers are a guarantee of failure.

In my case (4, Funny)

ptomblin (1378) | more than 5 years ago | (#27530965)

It usually "fails" because it went through the washing machine in my pants too many times.

Re:In my case (3, Interesting)

ebubna (765457) | more than 5 years ago | (#27530985)

such a good feeling when these stupid things still work after a wash

Re:In my case (4, Funny)

MindlessAutomata (1282944) | more than 5 years ago | (#27530991)

In that case, what's truly "failing" is you.

Re:In my case (5, Funny)

Yvan256 (722131) | more than 5 years ago | (#27531151)

You have a washing machine in your pants?

Re:In my case (3, Funny)

Anonymous Coward | more than 5 years ago | (#27531399)

How do you sit?

Re:In my case (5, Funny)

Chyeld (713439) | more than 5 years ago | (#27531457)

That's just what all the guys call it...

Re:In my case (1)

mea37 (1201159) | more than 5 years ago | (#27531519)

"Yo dawg, I heard you like..." No, that's not quite going to work out, is it?

Re:In my case (1)

Raven_black (453663) | more than 5 years ago | (#27531573)

Thats even better than having extra battries

Re:In my case (2, Interesting)

scorp1us (235526) | more than 5 years ago | (#27531171)

Why would a solid state device fail from multiple submergings? Especially if there is no current running through it during said submergings?

Re:In my case (5, Informative)

CRCulver (715279) | more than 5 years ago | (#27531221)

Because the water is not pure and there are corrossive elements in it.

Re:In my case (2, Funny)

uncledrax (112438) | more than 5 years ago | (#27531643)

Also, in my case, they usually make it to the dryer too..

I've learned to be alittle more careful.. but that doesn't mean they don't occasionally get a nice wash and dry :/

Re:In my case (5, Insightful)

AKAImBatman (238306) | more than 5 years ago | (#27531251)

Washing machines are pretty harsh places. You get tidal forces that will apply various physical stresses to the components. Rapid heating and cooling can cause expansion problems. Water can wear down contacts. Soaps can contaminate contacts or have negative chemical effects. So on and so forth.

If it makes it to the drier, your card could easily end up at temperatures outside the optimal storage temperature for the device. (Ever read those warnings, "Store between 70F and 100F?" Yeah, me neither.) These extreme temperatures combined with the rapidity at which they're introduced is a cornucopia of ways your device could be damaged.

In short, water isn't the real problem. It's all the stuff above and beyond that.

Re:In my case (2, Funny)

qwertyatwork (668720) | more than 5 years ago | (#27531565)

...Rapid heating and cooling can cause expansion problems.

Thats what she said!

Re:In my case (5, Insightful)

Bakkster (1529253) | more than 5 years ago | (#27531743)

Don't forget about the extreme static charges built up in a drier. Even though most USB devices have mechanisms to prevent static damage, a drier could overwhelm these protections. Regardless, usually a SSD failure should usually be due to the failure of the suport electronics, not the storage itself.

Re:In my case (4, Informative)

Moryath (553296) | more than 5 years ago | (#27531267)

Corrosion.

Being repowered while the internal circuit board is still damp with soap-contaminated water (shorting).

Physical stress ("agitate" cycle, "spin" cycle, Tumble Dry...).

Heat stress (which heat cycle did you use/did it go through the dryer too).

Need I go on?

Re:In my case (3, Insightful)

ptomblin (1378) | more than 5 years ago | (#27531277)

Usually the case falls apart. I can still get the data off the drive, but I stop using it and just spend another $20 to get something with 8 times the capacity of the last time.

Re:In my case (1)

bigdavesmith (928732) | more than 5 years ago | (#27531297)

I'm with scorp1us here. Being an idiot, I have sent my flash drives through not only the washer but also the dryer multiple times, and have never had an issue (thank god).

Re:In my case (1)

Razalhague (1497249) | more than 5 years ago | (#27531549)

I guess the type of pants you have and whether it stays in the pocket affect how rough a ride it gets.

Re:In my case (2, Interesting)

Anonymous Coward | more than 5 years ago | (#27531207)

Mine is a beast. I washed it at least twice, still worked, and then most recently ran over it twice. Once backing up, and again coming back up the driveway when i 'forgot' it inside. Not realizing i had dropped it. I found it when i got home and it was crushed. Removed the metal around the USB connector since it was a pancake, plugged it in while holding it and the dang thing still worked. However since i'm lazy i don't want to hold it in forever so it's been retired.

Re:In my case (3, Insightful)

AKAImBatman (238306) | more than 5 years ago | (#27531283)

However since i'm lazy i don't want to hold it in forever so it's been retired.

There's a fix for that. [wikipedia.org] :-P

Re:In my case (1)

cashman73 (855518) | more than 5 years ago | (#27531373)

Is that a washing machine in your pants, or are you just happy to see me?

Re:In my case (0)

Anonymous Coward | more than 5 years ago | (#27531487)

Eh, my last lexar titatium died after being dropped in a puddle just once.
Serious..

Re:In my case (1)

Lumpy (12016) | more than 5 years ago | (#27531537)

Have you found that number?

I'm up to 6 on my 16 gig cruzer.

Also I found my missing 4gig that I lost in november. the snow melted enough that it appeared in the snowbank at home. A good rinsing in deionized water and it still works.

Boot (1)

Nuno Sa (1095047) | more than 5 years ago | (#27531003)

I have several boxes booting from flash. None failed yet (all less than 3 years).

I usually mount /var in the HDD array, if that's possible...

Flash fails ... (0)

sygin (659338) | more than 5 years ago | (#27531015)

very carefully.

Here's what it looked like for a friend. (5, Interesting)

Slartibartfast (3395) | more than 5 years ago | (#27531017)

He'd taken it out of his camera, tried to put it back in, and nothin'. Slapped it into my Linux box. It "saw" that there was a device there, but wasn't real happy about it:
[ 5555.618324] sd 4:0:0:0: [sdb] Add. Sense: No additional sense information
[ 5558.777567] sd 4:0:0:0: [sdb] Sense Key : No Sense [current]

"It's dead, Jim."

I'm tempted to try the old hard-drive swaparoo: get the exact same SD card, unsolder the flash chips, and put the bad one's flash on the new one's circuitry. See if it's the circuitry that's bad, or the flash, itself. If anyone has any bright ideas on how to determine definitively which it is without me going through that exercise, I'm all ears.

Re:Here's what it looked like for a friend. (2, Interesting)

grahamsz (150076) | more than 5 years ago | (#27531381)

Firstly, "getting the exact same SD card" might be a challenge. I've bought various cards from the same manufacturers and they tend to have subtle variations.

Secondly I believe there isn't really much on an SD card except for the flash chip. CF cards have more of a traditional controller on there. A lot of the early criticism of SD was that a poorly made reader could screw up your card.

Re:Here's what it looked like for a friend. (1)

jweller (926629) | more than 5 years ago | (#27531515)

open it up first, a lot of them are just a solid chip now, not flash soldered to a board.

Burnt out (2, Informative)

abigsmurf (919188) | more than 5 years ago | (#27531045)

From what I gather, the most common cause of failure is the flash getting fried. Dodgy card readers, pulling the card out when a voltage is running through it, the chips are very sensative to spikes in current or voltage and burn out because of it.

Re:Burnt out (5, Funny)

Samschnooks (1415697) | more than 5 years ago | (#27531351)

Dodgy card readers,...

That's what you get for buying a Chrysler product or any Detroit product. Try getting a Honda or Toyota card reader. Or if you're a yuppy, a BMW card reader. Although, no one holds a candle to the Japanese.

Re:Burnt out (5, Informative)

dasunst3r (947970) | more than 5 years ago | (#27531447)

I am currently taking a class on solid state devices, and we just talked about how MOSFETs would fail. Basically, a high voltage to the gate would create these electrons that have so much kinetic energy that they create pairs of opposing charges (electron-hole pairs) in what was supposed to be the insulator. These pairs of charges would create an internal electric field inside the insulator. This process reduces the barrier for tunneling to occur, so more electrons are able to tunnel through the insulator and do the same thing, creating a runaway effect.

For more information, look up "Time-Dependent Dielectric Breakdown" and refer to pages 293 and 294 of Streetman and Banerjee's "Solid State Electronic Devices" (6th ed).

Was there a point to this article? (2, Insightful)

Intron (870560) | more than 5 years ago | (#27531049)

If a cell fails, you can't read or write that cell.

If a gate fails in a page, you lose access to the page.

If a gate fails in the overall control logic, you lose access to the whole device.

Is there something I'm missing? Did you think there were oil changes or brake shoes? It's one silicon chip with metal on it.

Re:Was there a point to this article? (4, Insightful)

Sooner Boomer (96864) | more than 5 years ago | (#27531155)

If a cell fails, you can't read or write that cell.

If a gate fails in a page, you lose access to the page.

If a gate fails in the overall control logic, you lose access to the whole device.

Is there something I'm missing? Did you think there were oil changes or brake shoes? It's one silicon chip with metal on it.

What about redundancy and self-healing? How do those work?

Re:Was there a point to this article? (5, Informative)

Anonymous Coward | more than 5 years ago | (#27531217)

Those work behind the scenes, if they are implemented. You wouldn't know they had been activated. If you lose a gate in the redundancy circuitry, that dies as well.

Re:Was there a point to this article? (5, Informative)

scatterbrained (144748) | more than 5 years ago | (#27531699)

There's no redundancy or self healing in the hardware of a common USB flash stick. The illusion that there is comes from a flash controller chip that does a mapping between disk sectors and flash sectors and shuffles things in and out so you don't notice the failures until it can't compensate for them anymore.

Re:Was there a point to this article? (4, Insightful)

Vellmont (569020) | more than 5 years ago | (#27531611)


Is there something I'm missing?

Maybe the part where you assume everyone knows the above?

Or how about the part where the submitter is asking about typical failure modes, not all possible failure modes?

Re:Was there a point to this article? (5, Informative)

scatterbrained (144748) | more than 5 years ago | (#27531629)

If a cell fails, you can't read or write that cell.

If a gate fails in a page, you lose access to the page.

If a gate fails in the overall control logic, you lose access to the whole device.

Is there something I'm missing? Did you think there were oil changes or brake shoes? It's one silicon chip with metal on it.

Conceptually at least, there are several parts to worry about:

1 - the OS & storage driver
2 - the USB driver
3 - the flash controller
4 - the flash memory

At the flash memory cell level the usual failures are breakdown of the dielectric materials and trapping charges in the memory cell that prevent an erase from happening and yield 'stuck' cells. This is normal for /all/ flash chips and is why they all have an erase cycle rating. There are certainly more exceptional ways for the chips to fail (soldering, wire bond failure, static damage, etc).

The flash controller is supposed to be doing wear leveling, error detection and correction on the flash, to get around those problems with the flash chips, and also talking USB. These chips usually have a microcontroller in them somewhere, and there's probably bugs in that code, no doubt more in the parts that get exercised the least, like error paths :-)

The OS and drivers just have the garden variety bugs and features that we all know and love...

Re:Was there a point to this article? (3, Informative)

AvitarX (172628) | more than 5 years ago | (#27531771)

Having a broken SD card in my pocket, I will describe how it behaves (which I think is what the article is asking). It is a 1GB SVP.

In Windows (XP and Vista), it asks me to format the drive, chkdsk fails because the partition type is raw. Using recovermyphotos on it I get between 10 and 200 photos found before the card reader decides it is not in their anymore, and I can't recover the ones found (perhaps if I paid I could recover as it scanned).

On Linux cat /dev/sdb returns no media found (I assume this is card to card reader trouble again).

Interestingly, on a different reader that gives IO errors with every other card I use I get the raw partition do you want to format it issue.

The fact that I can't read the drive at all from Linux ended my exploration.

Re:Was there a point to this article? (1)

MightyYar (622222) | more than 5 years ago | (#27531799)

Is there something I'm missing?

Yes. You're theory does a good job, but you need to balance it out with the potential for "intelligent failure". That is, the failures are simply to complicated to explain without some kind of intelligent force at work.

Failure to Write (5, Informative)

Toad-san (64810) | more than 5 years ago | (#27531073)

Had two finally wear out. Both started giving "could not write to device" sort of errors. The system (Windows 2K or XP) would still recognize the drive, would show the files, etc. Indeed, I could still access (read) the files, so the data was there and copyable. But I'd get a file write error every time I read anything, because Windows was trying to update the flash drive's file directory with "last accessed" or some such, and that write would fail.

No biggie; copied the data to a replacement, threw the old ones away, after hitting them several times with a hammer to "clear" the memory :-)

Depends on the Filesystem I suppose (4, Informative)

grahamsz (150076) | more than 5 years ago | (#27531333)

On a modern filesystem, your writes should essentially be atomic and in theory it shouldn't be possible to leave the drive in an inconsistent state when the write fails.

Of course most camera memory cards end up being formatted with fat32 which can be a little less forgiving.

Re:Depends on the Filesystem I suppose (1)

Hatta (162192) | more than 5 years ago | (#27531511)

On a modern filesystem, your writes should essentially be atomic and in theory it shouldn't be possible to leave the drive in an inconsistent state when the write fails.

But when "consistent" means all your files are zeroed [launchpad.net] , that's not much consolation.

Re:Failure to Write (3, Interesting)

bkaul (1235970) | more than 5 years ago | (#27531633)

I had a 2 GB Micro-SD card in my phone fail on me; it also failed to write, but there was also data corruption of some of the contents that were already on the card.

The first symptom I encountered was that my backup program would report that it had failed to successfully back up the phone to the card. I popped the card out of the phone and into a PC, and noticed the data corruption in several places when trying to back up the contents - not just CRC read errors, but filenames actually turned to garbage, etc. in a couple of directories. After reformatting the card, the symptoms persisted - sometimes writes would fail, etc. Don't know what caused the failure, but that's what it looked like in my experience.

Fail on write (4, Insightful)

fishybell (516991) | more than 5 years ago | (#27531077)

The biggest difference I've encountered is when traditional hard drives fail, they fail on reading data back.

Flash media fails when you write the data. In theory this means that you can always recover data as you can never write data to bad sectors. In practice the entire media device (CF, SD, etc.) fails at once.

Re:Fail on write (3, Informative)

SatanicPuppy (611928) | more than 5 years ago | (#27531367)

It just seems like the traditional drives only fail on reads: they mostly do reads, so when they fail, it's more likely on a read.

I've had many a drive fail during writes though, usually at the worst possible time (deadlines, when the machines are getting read/write hammered, and then bam, drive goes down and RAID performace goes to shit, and people start whinging.)

I've had flash drives die all at once. It's not the norm, but there are things that can happen that will take them from "fine" to "dead" with no steps in between. Usually it's thumbdrives that that happens with; I haven't had a full flash harddrive fail at all yet, so I don't have any insight there.

Slow writes! (0)

Anonymous Coward | more than 5 years ago | (#27531093)

I gave up on my first flash drive after it took about 20 minutes to copy a mere 10Mb worth of data onto it. It's still readable, I just don't want to wait for it to find good sectors to write to.

Flashmemory (3, Informative)

Narpak (961733) | more than 5 years ago | (#27531107)

Maybe I am totally on the wrong track here but don't the fact that they can't use Lead in some of the alloys contribute to the lifespan of some computer parts?

As I understand it aluminium alloys created without lead and then used in computers degenerate several magnitudes quicker than alloys with lead. The process is apparently that the aluminium start sprouting tiny tiny "hairs" and when one of these connects to another one of these coming from somewhere else in the machine then it's thank you and good night for that part.

Anyway the reason I mentioned this is because apparently with intensive use 5-7 years is how long parts in your computer takes to make a connection and after that it is LED OFF (see what I did there?) Of course unless you have a computer constructed before the mid nineties (I think that was the point); since they use lead in their alloys this isn't something that will affect them (though a range of other issues will).

Re:Flashmemory (4, Informative)

EdZ (755139) | more than 5 years ago | (#27531199)

You're thinking of 'Tin whiskers', and I'm not sure they're an issue with Silicon chips (because, well, they're SILICON), and the amount of time it takes for whiskers to grow between SMT components shouldn't differ between SSDs and HDDs. Plus it's a very slow process anyway, especially in the atmosphere.

Re:Flashmemory (2, Insightful)

scatterbrained (144748) | more than 5 years ago | (#27531745)

google 'tin whiskers' and 'RoHS solder failures'

Re:Flashmemory (0)

Anonymous Coward | more than 5 years ago | (#27531813)

Lead... some wonderful, magical metal!

FAT (5, Informative)

AKAImBatman (238306) | more than 5 years ago | (#27531113)

The one account I have found detailed using a small USB drive for /var/log storage; it failed very quickly, and then utterly (0 byte unformatted device), after five years of service in the role.

Without knowing more about this specific situation, I'd say this failure sounds like it pre-dates wear leveling. Prior to wear leveling, the most used sectors were likely to fail the fastest. And what sector gets written to more than the file allocation table?

If the file allocation table was lost, that would explain why the device became completely inaccessible. The card might not be a total loss if the card contains firmware or circuitry to remove bad blocks from usage. In that case it might be possible to reformat it. (Of course, if it lacks wear leveling I wouldn't count on it.)

Wear leveling neatly solves this issue by shifting writes to different free blocks with every write. This assures that the maximum use of the card is obtained prior to failure. Should any given block fail the card will detect the checksum error, mark the block as bad, then attempt to rewrite to a different block. This is communicated back to the reader in a transparent way. As far as the reader knows, nothing happened.

As you can imagine, wear leveling makes it incredibly rare to see Flash failures these days. It can still happen, but the results are likely to be unpredictable. The card will need to chew through all free blocks before it starts returning errors. In that case you may be able to continue reading the media. Or it may fail like the USB drive you mentioned. It all depends on the importance of the block on which the erasure was attempted. Since you only know about a failure *after* the block erasure, you're at the mercy of the quality of the card's electronics and algorithms to protect against a dangerous erasure.

Re:FAT (5, Informative)

daid303 (843777) | more than 5 years ago | (#27531281)

Even with wear leveling devices still can fail easy. A single power failure during a write can ruin a perfectly good SD card. It took me a single try.

Most devices that do hardware wear leveling are not power fail safe. And get corrupted beyond repair, random data corruption may follow, or an unreadable device.
(I've done extensive testing with SD and Compact Flash devices in power fail cases. Because not all manufactures deliver what they promise)

Re:FAT (2, Insightful)

AKAImBatman (238306) | more than 5 years ago | (#27531397)

A single power failure during a write can ruin a perfectly good SD card. It took me a single try.

You're right, I think that's the most common situation people see these days. Most of the other posters are describing sudden, total failures. Which are consistent with frying the drive rather than failures of bad blocks. Not all that different than losing a head on a hard drive.

Re:FAT (1)

BlendieOfIndie (1185569) | more than 5 years ago | (#27531787)

Interesting - so are manufacturers putting capacitors inside of high-end SSDs to ensure that writes are written successfully? I would imagine so. Mechanical drives use capacitors to move the disk head to a landing pad to prevent head crashes after a power failure.

Re:FAT (1)

tzot (834456) | more than 5 years ago | (#27531419)

A lengthy post, but not necessarily relevant. Why do you presume that the flash USB drive used for /var/log storage was left with its original MS FAT/FAT32 file system?

Re:FAT (1)

AKAImBatman (238306) | more than 5 years ago | (#27531609)

Because very few people reformat their Flash drives to anything other than FAT? And even if they do, the principle is still the same. The MFT, superblock/inode table, Volume Header/Allocation File (depending on your FS) are all vulnerable to similar degrees. It's the nature of file systems that they tend to have a few weak points that don't mesh well with limited-write storage. That's why wear-leveling was applied to Flash media. The individual file writes might be well distributed, but the meta data was causing a number of early drive failures.

Re:FAT (0)

Anonymous Coward | more than 5 years ago | (#27531493)

This is communicated back to the reader in a transparent way. As far as the reader knows, nothing happened.

Are you of the lawyerly profession or perhaps a politician?

Re:FAT (1)

adam1101 (805240) | more than 5 years ago | (#27531569)

According to this Linux filesystem developer, wear leveling as implemented in consumer level flash memory is often pretty lousy: http://valhenson.livejournal.com/25228.html [livejournal.com]

like a CPU (2, Informative)

Lord Ender (156273) | more than 5 years ago | (#27531145)

I've been booting linux servers off of flash for a few years. For some of them, the whole OS, even /var/log, is on the flash drive.

I've had one drive fail, and it basically got hot and stopped being recognized as being connected by the computer. It was older generation technology, though. Newer flash technology designed for computers doesn't fail, as far as I have experienced. I'm talking about the flash SATA drives from name-brand manufactures.

Flash mail server (4, Informative)

ace123 (758107) | more than 5 years ago | (#27531167)

I had a 4GB FAT32 flash drive that I used as storage for a mail server attached to an OpenWRT router. It required renaming and deleting files all the time (every time it got an e-mail)--so I think it wore down pretty quickly.

One day, the storage for the flash drive stopped working (from one hour to the next, without being touched, the computer acted like I had just yanked the drive out)--it would be recognized but report a "no media in drive" error when you tried to access it, like an empty CD drive. In fact I think Windows would say "Insert CD" or "No disc in drive F"

The index perhaps? (1)

AnalPerfume (1356177) | more than 5 years ago | (#27531195)

Is it possible the first part the OS looks at, with the index of everything on the drive has failed and shows nothing when in fact the data is there. Not unlike a dual booting Windows overwriting a previous Linux MBR and "forgetting" to add the already installed Linux to the list of boot options. Linux is still there although there is nothing in the first part pointing to it. I dunno how flash works at this level so it may be bullshit, but I thought I'd throw it out there; you never know.

Anandtech 'splains it all (4, Interesting)

spyrochaete (707033) | more than 5 years ago | (#27531211)

A few weeks ago /. linked to a really wonderfully written article by Anand Lal Shimpi about SSD drives. In the article he includes some simple and clear explanations of how flash memory works, its lifespan, and how it handles writes and deletes to maximize the life of every block of storage.

http://www.anandtech.com/printarticle.aspx?i=3531 [anandtech.com]

The only think missing from the article is a description of the behaviour of a failing drive.

Re:Anandtech 'splains it all (1)

dzfoo (772245) | more than 5 years ago | (#27531339)

>> The only think missing from the article is a description of the behaviour of a failing drive.

So what you actually meant is that "Anandtech 'splains it almost all".

An article that explains everything except what the original poster asked is not very relevant, is it.

      -dZ.

It depends on what and where (2, Insightful)

flyingrobots (704155) | more than 5 years ago | (#27531213)

If the flash drive fails, yes you can continue to read from it, but you also have to consider what is meant by reading.

You can always read the raw data from the device, that will never change. There is nothing that prevents the electrical signals from forming a proper read transaction on the IO pins of the flash IC chip.

However, when you consider the software that is on top of the raw data (a file system for example), this is where you will have the trouble.

With older CF cards, the concept of wear leveling was not implemented, I don't know about newer ones. This being the case, the directory structure for a file would more than likely reside in the same physical location on the flash. Opening, writing, closing a file with the same name would no doubt wear that space out as the directory entry gets hammered. Once that has "worn out", data is lost because the file system can no longer track it (even though the actual data may be viable).

Also consider the device that does support wear leveling. At some point it will run out of places to wear. Some large files will remain static and won't move (they are only read), some files will be moved all over the device by the device's ASIC as the data in the file is updated or changed. At some point, the flash will run out of cells. This could happen as some critical directory entry is being updated, and the whole file system could be corrupted because there are no more viable flash cells to use.

Your data might still be there is all its binary glory, but w/o a viable file system data structure to access it, well, you're toast. Unlike a harddrive that burped and lost a few bytes, a worn out flash drive has no recordable medium available to do any file system data structure repairs.

Kevin

gracefully... (2, Informative)

bdewet (546467) | more than 5 years ago | (#27531223)

I had flash failing on my 'gracefully'. The amount of available storage just becomes fewer and fewer after usage. It seems like the cells(if one can call it that) just dies after repetitive usage. Formatting does not help either.

can't always read after fails! (0)

Anonymous Coward | more than 5 years ago | (#27531225)

The urban legend about being able to still read flash after it fails is just that, an urban legend.

I've had 3 flash devices fail: two USBs and one SD. None were readable after their failures. On one I could see the directory structure but none of the contents.

First sector fails (0)

Anonymous Coward | more than 5 years ago | (#27531245)

The first sector is the most important sector of a flash card as it has the filesystem and other information for the rest of the card. In other words this is where the addressing for the rest of the card is stored, where you write to to format it, etc. It also contains bad sector information about bad sectors in the rest of the card.

When this first sector fails, the card is useless.

When cards are guaranteed to be "written to 10000 times", it means that the first sector has that guarantee. Cards usually ship with some bad sectors, with the card formatted and the first sector having the details of the bad sectors.

Didn't think they could (0)

Anonymous Coward | more than 5 years ago | (#27531265)

I was under the impression that unless something disastrous happened to the media, such as enough physical force to break it or spikes in voltage (or flawed materials/workmanship) they were pretty much reliable indefinitely. I have a Simple CF card that's over 10 years old in regular use with no problems, and have read about a photographer who dropped his camera in deep water and a diver recovered it a year laterâ"the camera of course was useless but all the photos on the card were recovered and the card was still useable. I would imagine that the technology used for larger drives now would be able to withstand similar abuses.

CF (4, Informative)

psergiu (67614) | more than 5 years ago | (#27531279)

Some years ago i used a 64Mb CF to install a minimal Debian on a IBM PC110 with 8Mb of ram. As the install process wanted more memory i created a 12Mb swap partition.
Big mistake.
The install took a whole day. I happily ran some programs the next day and crash - kernel screams of i/o errors in the swap partition.
Formated the card MS-DOS - it found a few bad sectors. Then i ran Norton Disk Doctor and at every run it was founding more and more bad sectors. But each time i was re-formating the card using a camera, the bad sectors were shifting around. Unusable.

FYI: IBM PC110 is a 486 Palmtop with a CF slot to be used as hard-drive. The CF interface is IDE.

Re:CF (1)

Jeff DeMaagd (2015) | more than 5 years ago | (#27531541)

Sounds like a defect in the wear leveling system. Not that I really understand how wear leveling is done in practice. I understand the idea of trying to spread the writes over the whole device, I just don't know how they actually keep track of that block mapping.

More recently MFG'd flash has more writes. (1)

bjamesv (1528503) | more than 5 years ago | (#27531687)

For ~3 years now ive been using a swapfile on a 2GB Kingston micro-mmc card with my nokia tablet (only 64meg ram)

after running an 8Meg file as swap i got a scare maybe 6mo back when i was unable to write a new file to the card - I thought, I'd finally done it: id burned through my writability -

after some close inspection though, i'd just hit the FAT file-per-directory limit. oh -ho :P

Recently ive actually increased the file to 64Meg to swap out more stuff for gaming with large Roms.
Honestly Im amazed the card has lasted as long as it has - considering i thrash the system near-constantly - with my new usage patterns, i'd still estimate the card has another 2 healthy years of service.

Wear leveling (1)

scorp1us (235526) | more than 5 years ago | (#27531287)

The wear-leveling concept would certainly work to favor a long, normal operational lifetime punctuated by an epic fail.

I would expect corruption of blocks - some take the new values, others don't. There is also the concept of t he bad-block list which might work well enough to begin shrinking the available blocks, possibly to zero, as the one failure you mentioned described.

one failure (0)

Anonymous Coward | more than 5 years ago | (#27531319)

I had one fail a couple months ago. It was pretty old (a few years at least, 256MB). I used it as an encrypted store for ssh keys and other things. I think the encryption is what wore it out so quickly (and maybe that it was older technology). It just started losing the partition table randomly. It still works for about 5 minutes at a time, though.

It's me, Slim Shady (0)

Anonymous Coward | more than 5 years ago | (#27531329)

I'm Anonymous
I'm the real Anonymous
All you other Anonymous'
Are just Pseudonymous

The short answer... (2, Informative)

earnest murderer (888716) | more than 5 years ago | (#27531331)

Your flash memory is fine, the controller is hosed.

This kind of (essentially unrecoverable) failure will continue to be an issue wherever the logic is integrated with the storage.

If it's any consolation, except for those who are always forgetting to "eject" or turn off their device before removing the media this kind of failure should be quite rare*.

Enjoy.

*Mfr's producing shoddy products not withstanding.

Re:The short answer... (1)

multipartmixed (163409) | more than 5 years ago | (#27531481)

> If it's any consolation, except for those who are always
> forgetting to "eject" or turn off their device before removing the media

Out of idle curiosity, you don't know why it is that when I eject my media the whole card reader gets turned off, do ya?

Stupid thing makes me mental, if I eject the card, I have to unplug the card reader and use the card. I've given up and just yank willy-nilly. So far the media seems to be holding up (probably about 1,000 inserts on this memory stick duo...)

Not formatted (1)

Hognoxious (631665) | more than 5 years ago | (#27531385)

I found an old 10MB CF card tidying some boxes the other day. Plugged it in and it said device (or disk) not formatted.

As to how old it was, it came bundled with the Kodak DC120 I bought on promo when that model was superceded.

I wonder what was on it - at 10MB, probably not much!

Suddenly (0)

Anonymous Coward | more than 5 years ago | (#27531391)

So far I've only encountered sudden failures, where the whole medium becomes inaccessible at once, probably due to some mechanical failure, e.g. miniature cracks in traces or bad soldering points. SD cards are particularly flimsy devices which should not be subjected to bending stresses at all. Take a broken one apart if you don't believe me.

flash faliure (5, Interesting)

erbbysam (964606) | more than 5 years ago | (#27531437)

About 5-6 years ago, I decided that it would be a good idea to build a small application on a flash drive, that is, code and compile it directly to the drive.
After what must have been hitting compile a few hundred to a thousand times, the 128MB thumb drive starting giving me drive write errors and then stopped responding altogether within about a minute after errors starting appearing.
I think the moral of this story is backup your data, even when it's on a flash based drive, and don't code directly on a cheap thumb drive :)

4GB SDHC card doing weird (1)

Lord Lode (1290856) | more than 5 years ago | (#27531449)

I have a cheap 4GB SDHC card. I've used it only a few times to take photos. Sometimes if it's in my camera, the camera gives an error that there's no card in it. After removing it and putting it back, it works again. And if I put it in the card reader in my PC, same thing: Sometimes mounting it in Linux works, sometimes it doesn't and it's as if nothing is in it. Removing it from the reader and inserting it back may make it work again. Could this be due to bad copper contacts on the SD card?

Strange partial-fails of SDHC cards.. (1)

kryptkpr (180196) | more than 5 years ago | (#27531475)

I was given a 4GB SDHC card by a friend, frantic that all her photos had disappeared. She did not do anything do physically damage the card, it was sitting in her camera and just suddenly started showing 0 photos one day when she turned it on.

I popped it into my linux machine and started to dd all the data I could get off of it. The first 512MB were fine. The next 512MB were completely unreadable. The last 3GB were fine.

Not sure exactly what could cause this type of partial failure, but it certainly seems like SHDC cards are actually multiple devices internally connected together, and it's possible to have just one fail at a time. Alternate explanations are welcome.

(VirtualBox + XP + Kernel FAT NTFS did the trick by the way, was able to save 80% of the photos).

Because people focus on the GB... (5, Informative)

blind biker (1066130) | more than 5 years ago | (#27531485)

...and quality and longevity take a back seat. So companies stopped offering SLC Flash RAM (+100.000 writes) and only offer MLC (5000 writes), and are now pushing even eight-level MLC, which will be even less reliable than standard 4-level MLC Flash RAM. But who cares, the consumer will be slightly fucked after a while, but that will be much later, after they enjoyed the happiness of getting slightly more GB for their buck.

The only manufacturer that I know of, that is an exception, if Kingston, which still offers SLC Flash products - namely their elite pro line of SD and CF cards, and the Data traveler USB drives. But that's it, everyone else has not completely transitioned to MLC.

Re:Because people focus on the GB... (0)

Anonymous Coward | more than 5 years ago | (#27531737)

Except you don't seems to consider wear leveling in your rant.

Physical Abuse (1)

CokeJunky (51666) | more than 5 years ago | (#27531507)

I have never had a flash drive long enough to wear out the flash cells, and I can't say I have seen them fail electrically.

I have however gone through at least 5 usb keys over the last few years, all due to physical abuse:
-Laundry (went through at least twice without failing, 3rd time's the charm)
-Loose/worn USB contacts: at least two different drives, after that I stopped buying the cheapest ones available
-Soup: Spilled in my bike bag, and caused the usb key to corrode internally, and probably caused a short because I didn't notice the soup had leaked into the casing until after I plugged it in
-Clumsiness: I dropped one on a hard wood floor, and then rolled over it with my desk chair. Another one broke the USB contacts off when I tripped and banged it with my leg. At least that one left a nice bruise in self defense.

I would love to see a completely sealed usb key that uses something like the Apple laptop power cable connections (mag safe, I think it is called) for the connection. Perhaps if it had a titanium case and complete water-proof seal, it might survive my abuse for more than 3 months!

this is a good freaking question. (3, Funny)

nimbius (983462) | more than 5 years ago | (#27531547)

ive been able to roll over a flashdrive with my car, wash, and bake a flashdrive in the process of doing laundry, and its never failed...however ive had one on my desk for a month that failed like a whale for no good (read:user abusing it as normal) reason. blaming gremlins, jeebus, and FSM until a solution abounds.

Corruption (0)

Anonymous Coward | more than 5 years ago | (#27531559)

I've never had an old one fail yet (usually they are replaced with larger/faster drive before it fails) but I did have one defective drive. It had a problem with random data corruptions similar to what you see when a drive has bad sectors.

Wash/Dry (1)

chrisgeleven (514645) | more than 5 years ago | (#27531563)

I have managed to wash and dry my flash drive numerous times and it still works. I make sure I have a backup of any important data on there of course, but I have been pretty impressed with how durable these flash drives have gotten.

FAT Failure (2, Insightful)

ArcherB (796902) | more than 5 years ago | (#27531691)

When I was in the digital imaging kiosk business, we had to repair about three flash drives a week. A customer would put it in one of our systems and pull it out while it was being read, or it was a cheap drive or whatever. Either way, the customer would blame our systems for killing their drives (rightly or wrongly). Of course, it would contain pictures of their dead grandfather or ex-girlfriend naked or whatever was completely priceless and irreplaceable.

The vast majority of the time, we would be able to run an application that would be able to recover whatever was on the drive. While I'm not certain of the original problem, the system acted as if the drive had no FAT (File Allocation Table... do I really need to say it?) on it or the FAT had become corrupted. This particular application would be able to go in and recover whatever was on the drive and most of the time repair the drive to its previous working state.

I say it ACTED like the FAT was corrupt, but I don't know or care if a flash drive has a FAT on it. Could have been a hardware thingie in there that hiccuped. The repair utility acted much like a scan-disk that would repair an MBR or FAT and/or act like an undelete utility would, restoring the files on the drive.

Adobe Flash fails (1, Funny)

Anonymous Coward | more than 5 years ago | (#27531697)

Because it's proprietary and sucks ass technically too.

After having worked with thousands of chips... (1)

Drachs (29694) | more than 5 years ago | (#27531701)

In my linux product which runs off compaq flash I can tell you that:

You often see lots of garbage and complaining in dmesg.

The flash chip fails to overwrite files properly. So that when I overwrite the file and try and read it back I get garbage.

Often the flash chip seems to have successfully overwritten the files and you don't realize anything is wrong until you reboot.

And... They don't last anything like the number of writes they pretend to. If you put even a light write load on a flash chip for any extended duration (Few days, few weeks) it will blow up.

David

'Flash' wear: Static, Connector Wear and Filesys (1)

billsf (34378) | more than 5 years ago | (#27531725)

Most removable 'flash' media probably dies from ESD and wear of the connectors. I've never knowingly lost one, but from the destroyed ones brought to me, it looks like static or possibly 'hot insertion'. 'Flash' is ideal for static file systems like /usr or /, etc. I use an image of the memory on hd and simply do something like dd if=/dev/image of=/dev/flash bs=16k. Systems that use inodes (just about all) are best and MS file-systems that use FATs are the worst. Even if you must use FAT file-systems, copying a formatted image to hd with dd and using it (the hd) to manipulate data and then putting the _whole_ image back with dd will never wear out. (over 1.000.000 cycles possible)

So to make it simple: Read from the flash and write to it sequentially before power is removed. This is the Unix solution. I'm not that sure if Windows can do it. Also write times will be up to 100x faster, often greatly exceeding the rated speed which is based on the FAT that it comes pre-formatted with.

BillSF

   

Have done some extensive testing... (5, Informative)

spock_iii (1152403) | more than 5 years ago | (#27531729)

For a prior employer, I had set up a process to qualify flash media for use in embedded products. There's a couple of different failure modes you are likely to see.

First off, when the actual flash media itself wears out, it takes longer and longer to erase individual sectors.

A flash device such as a USB stick or a CF card is slight more complicated because it has something known as an FTL (Flash Translation Layer). The FTL has the job of implementing the virtual media to flash sector translations, implementing wear leveling, and handling the awkward page erases. (Multiple sectors in a page, but you can only erase full pages.)

The FTL obviously must store some mapping information in the media in addition to your data.

If you start writing flash media, and time those writes, you see an initial rapid growth in the write timing that evetually levels off as the FTL tables swell to their constant operational size.

The over all flash write speed will level off to some average value that follows slow growth over a very very long tail as the media wears.

Early flash chips supported about 10,000 erases per page, and modern chips shipped by Samsung and others support a couple million erases per page. When you consider this is spread over say 4GB of media, you can understand that tail is very very long and flash media are probably comperable to hard drives in their MTBF these days.

Secondly, when flash actually does begin to fail, the media itself tends to exhibit a small number of different symptoms.

The flash may stat to show occasional data corruption when read. You might also have instances where data persists in the media only so long as power is applied. And then of course you have the fact that erases take longer and longer to achieve. Eventually erases or programming start timing out occasionaly.

With the FTL between you and the flash, you don't directly observe these effects. Presumably the FTL is smart enough to try and re-map your data elsewhere. In most cases there's ECC to attempt correction of moderately corrupted data. The real killers are when the data fails to persist after power cycling, when ECC fails to recover critical FTL data tables, or when there are no more spare sectors to re-map data too.

Those first two critical errors are likely to produce the lightbulb effect where your flash card or USB stick one day simply fails to come up when probed after device insertion. In more rare cases, the lack of spares may show up as some sort of reported write failure in your kernel logs assuming the flash device reports proper IDE/ATAPI/??? error data.

One final note -- please don't leave your USB stick inserted in the PC as you power it off! USB ports supply power and use a FET device to control that power. When you turn off the PC, the gates float and significant leakage current goes to the USB device. Some of the cheaper USB drives lack a key resistor that bleads this current away and protects the flash memory chips. This leads to data corruption. I have seen the FTL break in such sticks simply by doing POR on the PC.

Oh...almost forgot. When you put you flash stick through the washer and dryer, always use fabric softner or Bounce strips to reduce the static. :-)

Flash Failure (1)

RDanW (1293566) | more than 5 years ago | (#27531731)

I have had 2 fail on me within the last year. The first was a Corsair Survivor http://www.corsair.com/products/survivor/default.aspx [corsair.com] Was a pretty rough and tumble device but I guess it couldn't stand pottery dust. Within 4-5 months Windows nor Mac would recognize the drive. I kept a backup of it and called Corsair. They were very cool about it and asked that I return it. I sent it back and received a replacement for the drive within a few business days of them receiving it. I want to say that it was sent back to me via UPS Second Day. The drive itself wasn't handled to roughly so I have my doubts that it wasn't just a hardware problem from the start. Second one that is on its' way to failing is an Imation Clip Drive http://www.imation.com/en/Imation-Products/USB-Flash-Drives--Accessories/Clip-Flash-Drive/ [imation.com] . It is intermitantly failing to transfer files. I ran a version of Portable Apps http://portableapps.com/ [portableapps.com] and am also starting to see the Imation have a few problems. I'll probably not get the clip flash again because dust and dirt gets into the rubber boot and falls into the USB sheeth.
I work in an environment that can get pretty dirty, http://www.hlchina.com/ [hlchina.com] But what should I expect from a pottery. On the positive side, i've had about 3-4 SD cards that I transfered over from my Palm Zire that are now being used in the wife's camera and they refuse to die.

!Adobe Flash (0)

Anonymous Coward | more than 5 years ago | (#27531777)

It's too big to fail.

miniSD (1)

vaderj (1035706) | more than 5 years ago | (#27531801)

After only a year i had a 1g miniSD in my vx8100 slowly start having read/write failures. It acted just like it was having bad sectors that were expanding just like on a disc drive

2 common failure modes (in my experience) (1)

annoyed by procedure (973327) | more than 5 years ago | (#27531807)

In my business I handle a lot of SD, SDHC, and CF cards every week. First failure is very common, maybe universal, in SD cards: as it comes from the factory, the card works fine in digital cameras and readers attached to computers, but in a Windows Mobile PDA (all five different Dell and HP models I've tried), a small number of files in folders copied from Windows XP or Mac don't show up--the folder's there, but the file inside isn't. When I look at it on a reader on the original Windows XP or Mac OS X, the file is there and I can copy, open, etc. It's perfect. But no WM device can see that file. The problem seems to get worse the more the card is used. After formatting the SD card in the Windows Mobile PDA itself using a formatting utility, it works perfectly on all devices. Folks on forums have said that formatting it in a digital camera also prevents/fixes the problem. Reformatting it on Win XP or Mac doesn't help--same problem as when factory fresh. I don't know if other formats suffer from this--I now format every card in a PDA as soon as I get it to head off problems. Problem 2 comes up when someone yanks a card out of a card reader without following the computer's proper procedure for doing so. Some files can't be accessed, and sometimes the file and folder names are converted to gibberish. It's luck of the draw: 9 times out 10, there's no voltage flowing when you yank the card and you'll get away with it so maybe you'll think it's safe, but keep doing it and eventually you'll toast a card. To do it right on a Mac, drag the card to the trash, or select the card and enter command e, or Control Click on the card and choose "eject" or "safely remove" (I forget which). In Win, right click on the card and choose Eject. In Windows, if you've named the card, then when after choosing Eject the name of the drive changes from the correct name to "Removable Drive," it's safe to remove the card from the reader.

Like this: (1)

xlotlu (1395639) | more than 5 years ago | (#27531821)

This is how it looks in linux: http://paste.ubuntu.com/127979/ [ubuntu.com]
IIRC that was the secondary SSD in an eeepc 900. Not sure what the windows variant of this would be.. BSOD?

My experience... (1)

nate_in_ME (1281156) | more than 5 years ago | (#27531823)

We had a flash drive where I used to work a few years ago that for whatever reason(don't remember why any more), the plastic housing had broken off. We were able to use the unprotected chip as a working drive for at least another 3-4 months before it eventually decided it couldn't take any more abuse.

Catastrophically. (1)

clone53421 (1310749) | more than 5 years ago | (#27531855)

N/T.

But if you want a more detailed description, I'll acquiesce.

I've had 3 flash drives fail.

One failed because of cheap manufacture. The repeated use finally caused the solder to crack where the USB plug was mounted on the PCB. I was able to resurrect it with some careful soldering, but it eventually happened again, and I eventually wasn't able to get it working again. AFAIK, the actual device was fine, other than the loose plug. The body was made of cheap plastic, though, so it wasn't really a huge surprise.

The 2nd and 3rd flash drives that failed [everythingusb.com] were a bit more of a disappointment. Apparently they had some sort of on-board firmware that got corrupted, because somehow they were totally bricked. The computer wouldn't even recognise that a device was plugged in. The blue LED would very briefly flicker when they were inserted, then nothing. I got the first one replaced under warranty, and when the same thing happened to the second one within a month, I basically said fuck this. I blame it on loose USB connectors in the lab computers I was using, but still - a loose connection shouldn't brick the device. Data corruption would be understandable, but the entire device dead? Not so much.

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