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Which RAID for a Personal Fileserver?

Cliff posted more than 10 years ago | from the how-much-redundancy-can-you-handle dept.

Data Storage 898

Dredd2Kad asks: "I'm tired of HD failures. I've suffered through a few of them. Even with backups, they are still a pain to recover from. I've got all fairly inexpensive but reliable hardware picked out, but I'm just not sure which RAID level to implement. My goals are to build a file server that can live through a drive failure with no loss of data, and will be easy to rebuild. Ideally, in the event of a failure, I'd just like to remove the bad hard drive and install a new one and be done with it. Is this possible? How many drives to I need to get this done, 2,4 or 5? What size should they be? I know when you implement RAID, your usable drive space is N% of the total drive space depending on the RAID level."

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RAID 1 (5, Informative)

Oculus Habent (562837) | more than 10 years ago | (#9444757)

For personal use, a two-drive RAID 1 is probably the easiest way to go, and involves the fewest drives, but loses the most space (half). Raid 5 is the standard, but the hardware is more expensive and it involves at least one additional drive.

For simplicity and low expense, even though you lose a full drive worth of capacity, go with RAID 1.

You might want to read The Tech Report's recent article [techreport.com] mentioned on Slashdot [slashdot.org] if you haven't already.

Re:RAID 1 (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#9444786)

/me closes thread.

Re:RAID 1 (0)

Anonymous Coward | more than 10 years ago | (#9444788)

Of course, one hard drive (since the other is used for mirroring) hardly makes a file server now does it?

Re:RAID 1 (3, Informative)

Linux_ho (205887) | more than 10 years ago | (#9444919)

Of course, one hard drive (since the other is used for mirroring) hardly makes a file server now does it?
Whether it's a file server or not doesn't depend on the amount of available drive space. And considering the size of current hard drives, for a *personal* file server, I would expect very few people would find it necessary to buy a hardware raid controller.

Re:RAID 1 (0)

Anonymous Coward | more than 10 years ago | (#9444949)

*shrug*. I couldn't imagine living with so little space. Any serious computer user should have far more to store than that. Hell, I have more than 2.5 terrabytes just in porn.

Re:RAID 1 (5, Informative)

Anonymous Coward | more than 10 years ago | (#9444887)

You should really try out some of the SATA RAID solutions. They offer the best bang for your buck. I know that the next time I have a few hundred dollars lying around I'm going to go with a 1 TB RAID 5 with some WD SATA 250s [westerndigital.com] . Also, Supermicro [supermicro.com] makes a very nice 5 drive chassis [supermicro.com] that only takes up 3 - 5.25" bays. This is the ideal home setup in my mind.

Software raid (2)

Rei (128717) | more than 10 years ago | (#9444965)

What I really want to know is what sort of performance you get from software raid solutions. After all, the concept of being able to get redundancy without forking money over for a raid card (even from ebay, they're expensive), is rather tempting.

Re:RAID 1 (0)

Anonymous Coward | more than 10 years ago | (#9444947)

The only problem with RAID 5 is if two drives go down, you're totally screwed. Of course, it's relatively rare that even one goes down, but imagine what would happen if a manufacturer produced a bad lot of drives; if you bought, say, 6 drives from a supplier, they're likely of the same lot, and thus if there's a defect two might go down. If you're diligent enough and fix the bad one right away, then you're probably fine (unless, while you're rebuilding the array, another one goes down in the process!).

search the fscking google (1, Informative)

Anonymous Coward | more than 10 years ago | (#9444763)

Um.. Have you done any research into RAID? Anyone with even the most basic understanding of RAID (such as someone who read the short guides that come with their RAID cards) would agree that if you have more than two hard drives, the way to go is RAID-5. Your storage space is N-1. If you have six 100gb drives, your storage space will be 500gb. If you have a problem, you remove the bad drive, replace it and reinitialize the RAID arrive.

No offense intended, but why didn't you just do a google search rather than asking 1.5million slashdotters? The words "raid type" would have produced a nice table from adaptec and ars technica as the very first result that would have explained what you needed to know:

http://www.ebabble.net/html/types.html [ebabble.net]

Re:search the fscking google (0)

Anonymous Coward | more than 10 years ago | (#9444799)

Totally. Was this question worthy of Slashdot's index page?

Re:search the fscking google (3, Funny)

PoderOmega (677170) | more than 10 years ago | (#9444808)

Thank you for fulfilling the "Why didn't you check google?" quota. No one else needs to this until the next Ask Slashdot!

Re:search the fscking google (3, Insightful)

boarder8925 (714555) | more than 10 years ago | (#9444810)

but why didn't you just do a google search rather than asking 1.5million slashdotters?
Because it's better to ask people's opinions and stories than to simply read pages.

Re:search the fscking google (0)

Anonymous Coward | more than 10 years ago | (#9444844)

But his question has little or nothing to do with opinion. RAID types are RAID types. You decide what your requirements are, then you find the RAID type that fulfills those requirements. He clearly stated his requirements and could have found which RAID type fit by doing a two second google search, without any need (or room) for opinion.

Re:search the fscking google (5, Funny)

skirch (126930) | more than 10 years ago | (#9444825)

Another missed opportunity to use the internet's, uh, hottest new acronym: FGI [fuckinggoogleit.com] .

www.google.com (5, Informative)

baudilus (665036) | more than 10 years ago | (#9444875)

A quick note - if you re-initialize the RAID, it will erase everything you have. You should 'rebuild' the drive, unless you have a hot-swap, in which case you just take out the bad drive, pop in the good one, and ur good to go.

Re:search the fscking google (0)

Anonymous Coward | more than 10 years ago | (#9444886)

Perhaps it is an interesting topic? Perhaps the poster would like some personal experiences to help him avoid some pitfalls?

If you don't think the question is worth your time, read the headline, make your assessment, and move on.

Re:search the fscking google (1)

Joe5678 (135227) | more than 10 years ago | (#9444890)

The decision is not as simple as you make it. Sure RAID-5 gives you the most space while still giving you redundancy, but what happens if 2 drives fail? In a mirrored configuration you can lose multiple drives as long as you don't loose a mirrored pair.

Re:search the fscking google (0)

Anonymous Coward | more than 10 years ago | (#9444964)

If I had 4 drives I'd run Raid 5 and a hot spare.

As soon as a drive fails it rebuilds onto the spare. You're still ok if you lose another drive.

Re:search the fscking google (2, Insightful)

Lumpy (12016) | more than 10 years ago | (#9444904)

No offense intended, but why didn't you just do a google search rather than asking 1.5million slashdotters?

or how about starting with using high quality drives instead of dirt cheap consumer drives with low life and warrenty lengths...

I have had ZERO problems with my server quality SCSI drives that still have 2 years left on their 5 year warrenty.

I suggest looking at getting reliable drives before looking at a RAID solution.

Re:search the fscking google (5, Informative)

douthat (568842) | more than 10 years ago | (#9444908)

I was thinking the same thing regarding "why doesn't he just google RAID", but your generalizations do not take into account the data types of all users.
if you have more than two hard drives, the way to go is RAID-5
Not necessarily. If you have 4 drives and require exremely fast disk writes and reads (ie, video) and you absolutely can't lose data, RAID5 sucks. You should go with RAID 0+1, because you can have the performance of RAID 0 and 1, without the parity overhead and without a significant slowdown on drive failure.
If you have a problem, you remove the bad drive, replace it and reinitialize the RAID arrive.
When a RAID 5 array loses a disk, performance is severely affected, as each "read" to the missing disk must be calculated by reading the same sector from every disk and caclulating the parity. When you replace the faulty drive, performance will still be terrible untill the entire dataset is rebuilt, which can take hours on BIG/SLOW drives.

You also never touched on the possibility of him having only 2 drives, in which case RAID 1 would be the way to go for data redundancy.

Re:search the fscking google (1)

Zak3056 (69287) | more than 10 years ago | (#9444927)

Anyone with even the most basic understanding of RAID (such as someone who read the short guides that come with their RAID cards) would agree that if you have more than two hard drives, the way to go is RAID-5.

That is, unless the additional costs of something like RAID10 is justified based on the performance penalty of RAID5.

My ERP box has 8 15kRPM 18GB disks in a RAID10. The usable disk space is only 90GB, but that's enough for our purposes. The ability to potentially survive the failure or four individual drives is also a plus.

Re:search the fscking google (1)

IgnorantSavage (530289) | more than 10 years ago | (#9444963)

This is simply not true. There are trade-offs for all RAID implementations, and RAID 5 has significant disadvantages such as very poor write performance especially if you don't have non-volatile write cache. Read performance can also be less than RAID 1 for decent RAID 1 implementations (which are unfortunately rare).

Also, RAID-5 rebuilds are relatively slow and compute intensive (XOR computations). Low-end RAID-5 implementations can even have major data security problems due to the difficulty of getting good performance without sacrificing data safety. Software RAID-5s in particular are often not 100% safe.

As others have also said, I would strongly recommend RAID 1 for an individual situation unless you need a large (> 1TB) amount of space.

This is what I use on my personal PC, though I am considering setting up a RAID 5 server with a few TB of space. I have not, however, found a really good and inexpensive RAID-5 controller yet.

I am looking into Linux software RAID, but am not sure whether I can get reasonable write performance. I'm in particular not sure if it has support for NV write caching or what kind of NV to use if it does. Perhaps a solid state disk?

Second poast (-1, Troll)

Anonymous Coward | more than 10 years ago | (#9444768)

Re:Second poast (3, Funny)

Fooby (10436) | more than 10 years ago | (#9444814)

Moderate this one "redundant."

*ducks*

Just remember the RAID song (5, Funny)

192939495969798999 (58312) | more than 10 years ago | (#9444775)

RAID 0, you need a hero,
RAID 1, is equally fun,
but RAID 5 keeps you alive!

Re:Just remember the RAID song (0)

Anonymous Coward | more than 10 years ago | (#9444849)

Maybe it's just me, but unless your Arnold Swartzavertunrolyiagoheiven, one doesn't rhyme with fun

Re:Just remember the RAID song (4, Insightful)

strictnein (318940) | more than 10 years ago | (#9444894)

You forgot the final four lines to that song!

RAID 0, you need a hero,
RAID 1, is equally fun,
but RAID 5 keeps you alive!


RAID 5 - better keep an extra drive
Or you'll be down until the replacement arrives
RAID 10 is better my friend
Work doesn't stop when the drive comes to an end

Re:Just remember the RAID song (5, Informative)

PhuCknuT (1703) | more than 10 years ago | (#9444935)

Raid 5 runs just fine in degraded mode until your extra drive gets there. I have one right now using software raid 5 in linux with a dead member waiting to be replaced. 0 downtime or data unavailability so far.

Re:Just remember the RAID song (0)

Anonymous Coward | more than 10 years ago | (#9444940)

i've recently setup a four drive raid 5, (and spent much more than if i had just used my mb integrated 0,1 raid) i believe it'll be best in the long run, but the way these Western Digitals have been treating me, i'll need to wait 5 years to actually know. ;)

RAID -1 (4, Informative)

Mz6 (741941) | more than 10 years ago | (#9444778)

I would choose RAID-1.. because RAID Level 1 provides redundancy by writing all data to two or more drives. The performance of a RAID-1 array tends to be faster on reads but slower on writes when compared to a single drive. However, if either drive fails, no data is lost. This is also a great entry-level starting point as you only need 2 dirves. The downside is the cost per MB is high in comparison to the other levels. This level is often referred to as disk mirroring.

Raid 1 (0)

Anonymous Coward | more than 10 years ago | (#9444779)

Raid 1 needs only 2 drives but will only give you the capacity of 1 drive. i.e. 2 80 gigs will give you 80 gigs of space.

RAID 1.... (1, Interesting)

jsimon12 (207119) | more than 10 years ago | (#9444784)

I just got x2 250gig drives and mirrored them.

RAID 5 or RAID 10 (5, Informative)

strictnein (318940) | more than 10 years ago | (#9444787)

Try RAID 5 [acnc.com] or RAID 10 [acnc.com] (not to be confused with RAID 0+1 [acnc.com] ). This site has a nice overview of all the RAID options [acnc.com] . And, of course, Wikipedia has some info [wikipedia.org] .

Quick overview:
RAID 5 - Requires at least 3 HDs (many times implemented with 5 - can be used with up to 24 I believe). Data is not mirrored but can be reconstructed after drive failure using the remaining disks and the parity data (very similiar to how PAR files can reconstruct damaged/missing RAR files for the Newsgroup pirates out there). % of total space available dependent on number of drives used.

RAID 10 - High performance, but expensive. You get ~50% of the total HD space as it is fully mirrored. So, 1 TB total disk space nets you 500 GB total storage space. Your data is mirrored so if one drive fails you do not lose everything. However, if you experience multiple drive failure you can be in big trouble.

Re:RAID 5 or RAID 10 (1)

Ian Wolf (171633) | more than 10 years ago | (#9444926)

Hey, nice links. I never realized that 10 and 0+1 were different. A very subtle difference, but a difference none the less.

At home, I run 0+1 on my file server, which is the best my onboard RAID controller can handle. I've never been a big fan of RAID 5 and given that most 'cheap' RAID controllers don't support it has always pushed me to RAID 1 or RAID 0+1.

Raid is not an option (-1, Flamebait)

Anonymous Coward | more than 10 years ago | (#9444792)

RAID is for inexpensive disks

Re:Raid is not an option (1, Informative)

strictnein (318940) | more than 10 years ago | (#9444837)

blah... only asshats call it that :-p

Redundant Array of Independent Disks

Re:Raid is not an option (1)

fanfriggintastic (751454) | more than 10 years ago | (#9444873)

That's Independant, not Inexpensive.

Re:Raid is not an option (1, Funny)

sxtxixtxcxh (757736) | more than 10 years ago | (#9444933)

Raid Ain't "Inexpensive", Dumbass.

raid and ide channels (5, Informative)

TheCoop1984 (704458) | more than 10 years ago | (#9444793)

Whatever you do, never have more than one disk on an ide channel. Only one disk per channel can be written to at the same time, so you will get absolutely horrible performance if you get more than one hd per channel. If possible, get an ide raid card (if you can afford it) or a SATA card/mobo and drives, which dont have this problem

Re:raid and ide channels (1)

Short Circuit (52384) | more than 10 years ago | (#9444923)

Could you put one drive each at the master setting of the primary and secondary channels, and have another controller for CDROM/DVD/ZIP/etc?

Hardware (3, Funny)

DaveKAO (320532) | more than 10 years ago | (#9444795)

Wow inexpensive & reliable... Those are two words you don't see together too often.

Re:Hardware (0)

Anonymous Coward | more than 10 years ago | (#9444879)

Naw you can have those two, it just means it'll be slow.

Re:Hardware (0)

Anonymous Coward | more than 10 years ago | (#9444893)

No wonder he's suffered through so many HD failures.

Re:Hardware (2, Insightful)

Binestar (28861) | more than 10 years ago | (#9444899)

Wow inexpensive & reliable... Those are two words you don't see together too often.

"Good, Fast, Cheap: Pick any 2."

Raid-1 & Plan 9 (1, Troll)

Cyclotron_Boy (708254) | more than 10 years ago | (#9444797)

I hear good things about this combination.

RAID MIRROR (-1, Troll)

Anonymous Coward | more than 10 years ago | (#9444800)

Use a RAID MIRROR, a fully redundant copy of a drive. This will give you the best data security with two drives. This tip brought to you by ECFA.

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Raid 1, 0+1, or 5.. (3, Informative)

XaXXon (202882) | more than 10 years ago | (#9444805)

Your good options are raid 1, raid 0+1, or raid 5, depending on what you want..

Raid 1 is the safest.. just mirroring the drives, but it results in no speed increase..

Raid 0+1 does mirrored stripe sets -- you get the speed advantages of raid 0 with the full protection of raid 1.

Raid 5 is good middle ground. Raid 5 stores 1 drive's worth of parity. When you lose a drive, your system goes down (if you don't have a hot spare), but you throw another disk in and it'll come back up. You also get some speed increase over a normal drive setup. With RAID 5, you only lose a single drive's worth of capacity no matter how many drives are in your array, whereas with raid 1, you lose 50%.

Re:Raid 1, 0+1, or 5.. (2, Informative)

lsoth (446686) | more than 10 years ago | (#9444877)

Correction... The failure of a drive in a RAID-5 array does not result in system failure. The array works in a degraded state until the drive can be replaced or the hot-spare is rebuilt (if available).

It is able to work in degraded state by using the parity information to re-build the data from the failed drive on the fly.

Re:Raid 1, 0+1, or 5.. (2, Informative)

CerebusUS (21051) | more than 10 years ago | (#9444889)

Raid 5 is good middle ground. Raid 5 stores 1 drive's worth of parity. When you lose a drive, your system goes down (if you don't have a hot spare), but you throw another disk in and it'll come back up

Actually, with any proper implementation of RAID 5 you wouldn't lose functionality during a single drive failure, but you would suffer a performance hit because every read would require the drive controller to reconstruct the missing data from the checksums.

Replace the bad drive very quickly, though, because a second drive failure will result in wiped drives, effectively.

Re:Raid 1, 0+1, or 5.. (0)

Anonymous Coward | more than 10 years ago | (#9444895)

With RAID 5, you get faster reads, but slower writes. (since it has to read the parity drive's current data, read the current data drive's data, write the new data, and write the newly calculated parity. I think.)

Re:Raid 1, 0+1, or 5.. (3, Insightful)

afidel (530433) | more than 10 years ago | (#9444934)

RAID 0+1 sucks, it can only sustain a single drive failure. RAID 10 (1+0) can sustain multiple drive failures without data loss under the right circumstances. The cool thing about RAID 10 is that you can use a pair of mirrored drive sets and use software to do the striping at near zero cost and you get controller redundancy! (most people who do RAID 10 will use the built in RAID1 controller and an addon two port RAID controller)

Re:Raid 1, 0+1, or 5.. (1)

Eye of the Frog (152749) | more than 10 years ago | (#9444948)

Your system won't go down when you lose a drive. You can run without the extra parity drive. But if you lose another drive whie running like that, you're pretty much toast.

Re:Raid 1, 0+1, or 5.. (1)

rkuris (541364) | more than 10 years ago | (#9444971)

Raid 1 is the safest.. just mirroring the drives, but it results in no speed increase..

This is actually not true. There is a reduction in performance for writes (twice as much data must go through the bus), but if you primarily do reads, the load is supposed to be divided among the two drives. You don't need to read from both drives to verify the data is correct!

Since most webservers are mostly-read and some-writes, you often see good gains with RAID 1.

hmm (1)

guitarded (628498) | more than 10 years ago | (#9444806)

Couldnt all of this been answered by just reading over each type of RAID?

Try netcell raid xl (1, Informative)

Anonymous Coward | more than 10 years ago | (#9444809)

the controller is a little expensive, but it doesn't have the same performance loss as raid 5 cards.

Can get a 3 drive or 5 drive card.

I've got 5 200 Gb drives in a raid xl array and it works great.

Which RAID (1)

unts (754160) | more than 10 years ago | (#9444813)

RAID 1 for if a drive fails.

RAID 1 + 0 - same as above but with speed benefits

RAID 5 - Costly, write performance takes a hit but reads are good.

IMO these are the only ones that should be considered. I'm sure somebody will elaborate on the theory behind them...

Old PC + 4 channel raid controller = easy (5, Informative)

patniemeyer (444913) | more than 10 years ago | (#9444816)

I went through this last year and here's what I came up with for the best benefit to cost ratio with the lowest hassle. In short, take an old PC and put a four channel raid controller card in it to do RAID 5. Add a big extra fan for safety and you're done.

Here's what I came up with: Total cost about $1200 (probably less by now).

0) Red Hat Linux, ext3 filesystem.
1) 3Ware Escalade 7506-4LP card (64 bit card, but fits in 32bit slot)
2) 4x 250Gb Western Digital drives
3) Big fan.

At RAID 5 This yields 750gigs (715Gb after crappy GB conversion).

The 3Ware software has a nice web monitor interface and does daily or weekly integrity checks. It emails me if there is a problem - I did have one drive die already and replaced it easily.

Pat Niemeyer
Author of Learning Java, O'Reilly & Associates

All boils down to money (2)

baudilus (665036) | more than 10 years ago | (#9444819)

I work for a company that uses all types of RAID. I've experience with 2 bay, 8 bay, and 16 bay RAIDs, as well as RAID cards. If you want the cheapest option, just get a two drive system (either with bays or just a card) and use RAID1. It's basically drive mirroring.

Bottom line, you need to figure out how much you're willing to spend on this and then go from there and see what your options are. RAID5 is the hotness, but it's very expensive (easily over $10K for large capacity devices).

Re:All boils down to money (0)

Anonymous Coward | more than 10 years ago | (#9444918)

Bottom line, you need to figure out how much you're willing to spend on this and then go from there and see what your options are. RAID5 is the hotness, but it's very expensive (easily over $10K for large capacity devices).

What the fuck?

RAID5 is not expensive. In fact, RAID5 is the cheapest RAID available. Would you rather buy 4x200gb drives and wind up with 400gb usable (as with RAID-1 for example) or would you rather buy 4x200gb drives and wind up with 600gb usable?

Please to be explaining how the hell RAID5 is expensive?

RAID 5 (2, Informative)

1eyedhive (664431) | more than 10 years ago | (#9444824)

Best way to go is RAID5, do it in software with Linux isn't much of a headache unless you change the size of it. RAID 5 is N-1 where N is the size of a member partition, you don't have to use an entire disk. For instance, my setup: 80GB HD 120GB HD 200GB HD the raid 5 members are the size equivolent to the 80GB itself. the remaining space on the 120 houses the system and a few miscellaneous things, the remainder of the 200 is a 110GB file dump.

Just set up a mirror (1)

Linux_ho (205887) | more than 10 years ago | (#9444826)

RAID 1. Buy one extra plain-jane ordinary hard drive and use software mirroring, like Linux's md system. I've used this extensively with no problems. I have known other people to have problems using software RAID for more complex setups like RAID 5, but if all you need is extra reliability for a basic desktop workstation, RAID 1 in software is generally fine.

Here it comes... (3, Funny)

devphaeton (695736) | more than 10 years ago | (#9444827)

"I'm tired of HD failures. I've suffered through a few of them. Even with backups, they are still a pain to recover from.

If you just run Gentoo, you can type "emerge new_harddrive" and it takes care of everything by the end of the month!

or..

Your shit PEECEE WINTEL crap parts made in china are no match for real quality Mac hardware, which are fully integrated with the UNIX UNDERPINNINGS that have the Best GUI Ever(tm) on top.

Disclaimer: I love trolls.

Raid (0, Offtopic)

Anonymous Coward | more than 10 years ago | (#9444829)

Kills Bugs Dead. Stupid fuckin bugs.

Dear Slashdot (5, Funny)

ccwaterz (535536) | more than 10 years ago | (#9444830)

Dear Slashdot,

which is better, SCSI or IDE?

Googleless in VA

Re:Dear Slashdot (0)

Anonymous Coward | more than 10 years ago | (#9444909)

Dear Googleless,
Jostens has a whole range of metals to choose from--including platinum, white or yellow gold, and, for those of you who are minding your budgets, white or yellow Lustrium. Yes? Question? Okay, well, Lustrium is the least costly. But it's a good idea to look at all your options before you choose. See, Lustrium is what is called a non-precious metal alloy. While it is fairly durable, it does not have the same characteristics as gold or platinum and, in the long run, many customers feel their graduation is more... Yes? Okay, well, Lustrium is about half the price of 18-karat gold. But, like all fine jewelry, your class ring is an investment. I can answer all these questions later. What's that? Well, the final cost really depends on a number of factors--type of metal, engraving, size, style--so it's best to start looking through the brochure and determining which rings suit you before you look at the price list. That's the best way to narrow down your choices and design a personalized ring you're sure to love for the rest of your life.

Re:Dear Slashdot (1, Funny)

Anonymous Coward | more than 10 years ago | (#9444951)

Dear Googleless in VA,

You're new here, aren't you?

Slashdot

Re:Dear Slashdot (0)

Anonymous Coward | more than 10 years ago | (#9444952)

SCSI is better since IDE is an anagram for DIE.

Re:Dear Slashdot (1)

alexatrit (689331) | more than 10 years ago | (#9444968)

Dear Googleless,

Please be sure that your intarweb isn't broken before posting questions to Slashdot. Now get back to work, there are still tickets in the queue.

-- Mr. Google

My choice (4, Insightful)

Simon Carr (1788) | more than 10 years ago | (#9444831)

If I could, I'd get 2x 250GB HDDs in a RAID1 (promise controllers are good for this), and a third 250GB for a cold backup of all my data that syncs weekly.

Raid's great, but an rm -rf is still an rm -rf, thus the third drive :)

RAID complexity (2, Interesting)

ckaylin (193523) | more than 10 years ago | (#9444833)

It's axiomatic that the more money you spend for reliability the more likely you are to have some kind of failure. Our fancypants Dell PowerVault RAID enclosures are constantly giving us trouble, yet the machines with just a single IDE drive keep on ticking for years and years.

RAID 5 (1)

halfelven (207781) | more than 10 years ago | (#9444836)

Personal server? RAID 5, no doubt.

Raid 5 (2, Interesting)

silas_moeckel (234313) | more than 10 years ago | (#9444839)

If your running a fileserver with a decent ammount of writes yours going to want RAID5 as it has the least penalty. Hot swap drives are easy enough with SCSI or FC a bit more complicated with SATA and rather complicated with IDE but can be done. For a simple setup as little as 3 disks will do and you will get 2 disks worth of space performance setups will have more spindles. You didn't state as to what sort of load your expecting and that makes a huge difference. For the ultra cheap I have picked up IDE raid 5 cards supprting 4 drives with hot swap for sub 30 bucks on ebay they will only work with 120 gig drives max and are limited to ultra 66 but thats a third of a TB usable as well for a few hundred bucks and it's performance is good enough for a 100bt file server.

Software RAID (1)

enodev (692876) | more than 10 years ago | (#9444841)

If you don't need any fancy hotplug, just go with 2 or more IDE drives. If one fails you just have to shut down your pc, replace the drive and boot again. For Raid1 you'll lose half your capacity, for Raid5 you just lose the capacity of one of your drives.
If you need real hotplug you'll need to get some expensive scsi or ide (3ware) controller.

Whichever damn raid level you want! (4, Informative)

SeanTobin (138474) | more than 10 years ago | (#9444845)

Seriously. Raid is all about risk. Figure out how much risk is acceptable to you. If you have a stack of 6 drives and you only believe 1 is ever going to fail at any one time, then go with raid 5.

If you have a stack of 6 drives and believe not a single one is ever going to fail, go for level 0.

If you are a government contractor and are required to handle simultaneous failures of 75% of your drives, either mirror them all or go with 5+1 or a raid 10 setup.

All in all, its a poor question to ask slashdot. You need to let us know what you consider an acceptable failure, and by the time you have that figured out determining what raid level you need is easy.

RAID 5 or 6 (3, Informative)

Tr0mBoNe- (708581) | more than 10 years ago | (#9444846)

RAID 5 or 6 will stripe the data across all drives in the array. You will basically need about 8 - 10 % of the total space set aside for data recovery. You can loose 2 hard drives (as long as they are not next to eachother) and not loose any data. RAID 5 and 6 are only incredibly useful in application with more than 4 hard drives and about 500 gb of storage. It's a little faster than the lower raids becuase the redundancies are simple pairity bit calculations, and are done twice for each single data change on disk. The lower raids will have a set of disks that actually mirror the data in tact (raid 1) or perform more intensive Hamming Distance calculations and store the results on another set of disks.

So, RAID 5 or 6 would be the best (RAID 6 is worth the extra bit of space for the 2nd calculation, and really helps when you can test the pairity bits against another pairity to create the lost data.)

There will be some slow down associated with RAID, but it wont be as bad with 5 or 6 and generally, you can live through it with the thought of having relativly robust file servers.

Re:RAID 5 or 6 (1)

thefatz (97467) | more than 10 years ago | (#9444954)

How does RAID-6 fit into personal file server? Maybe a 9/5's SUN system, but wouldnt raid 50 or 10 be better at that point?

Raid-5 / 8 drives / 3ware controller. (0)

Anonymous Coward | more than 10 years ago | (#9444847)

First, a couple things.

Most IDE raid controllers are really software raid. 3ware makes real IDE raid controllers and I would recommend them for home users/Linux.

I would suggest (if it is affordable) to do a Raid-5 setup with 8 IDE drives. This easily gives you 1 TB, and *reasonable* cost and with *reasonable* redundancy. RAID-5 costs 1 drive for redundancy -- in this case meaning 12.5%. If one drive dies you are fine; two drives dying concurrently means you lose everything.

For smaller requirements, I would suggest using mirroring with a cheap built in RAID controller (=software). Cost of redundancy is 50%, but that is reasonable when you are only buying 2 drives.

STFW (0)

Anonymous Coward | more than 10 years ago | (#9444856)

Idiot...

What raid to use. (2, Informative)

Retric (704075) | more than 10 years ago | (#9444861)

If you want the best % of drive utilization go for raid 5. It works by Striping the data across 2 drives then XORing the data on the 3rd drive. But, you need 3 drives. Raid 1 works with only 2 drives but you only get 1/2 the data basically each drive has an exact copy of the data that the other drive has.

Put simply if you don't have a lot of data to store but you want it safe go for raid 1 with small drives you end up with the same data storage as one drive but it takes 2 drives. If you have a lot of data to store go for raid 5 you get twice the data storage of one drive but you use 3 drives.

RAID 1 (1)

edrugtrader (442064) | more than 10 years ago | (#9444862)

you want RAID 1.

raid 0 = not fault tollerant.
raid 5 = difficult to rebuild after fault.

RAID 1 is simply copying everything to every disk. after a failure put a new disk in and the controller should copy everything to the new drive.

RAID XL (0)

Anonymous Coward | more than 10 years ago | (#9444865)

RAID 0 speed with RAID 5 reliability

http://www6.tomshardware.com/storage/20031128/in de x.html

www.syncraid.com

RAID 5 w/ hot spare (2, Informative)

wfbush (136129) | more than 10 years ago | (#9444874)

A simple, very safe server setup is RAID 5 w/ a hot spare. One drive fails, the array rebuilds on the hot spare, and you replace the failed drive whenever you have a chance.

In theory, some of this is possible in software, but a good RAID controller card is much, much better.

Software RAID? (5, Insightful)

Suydam (881) | more than 10 years ago | (#9444876)

Have you thought about software RAID? Before everyone jumps down my throat, I realize that it's slower than hardware RAID...but, here is my rationale for using it:

1) You don't need drives that are the same size.
I've done hardware RAID, had a drive fail 2 years down the road and not been able to find an 18GB SCSI drive to re-insert to the array. That has the potential to jack your entire array. With software RAID, you buy a 36G drive, partition it so that 1 partition fits your array, and off you go

2) It's a personal file server, so speed is less important than cost (i'm guessing). With software RAID you can mix all sorts of wonderous things together. IDE drives from the basement, SCSI-320 drives you stole from work and nearly everything in between. It's for flexible, and has no associated controller cost.

3) It's easy as heck. You can configure it in Disk Druid/fdisk, and it works quite easily in any major distribution (I've done it in Slack, Debian, RH, Fedora and Mandrake).

The major downside is that you cannot (as least I don't know how to) hot-swap drives. But again, this is a personal file server. Spend your money on pizza and beer, screw the SCA hot-swap drives that are going to cost you an arm and a leg.

That's just my $0.02...flame away

Re:Software RAID? (2, Insightful)

wfbush (136129) | more than 10 years ago | (#9444928)

Yeah, for a personal file server, software should be good enough, but I wouldn't risk it for a "real" server. You can even use IDE/ATA/SATA drives, although there it gets more complex if you want more than 4 drives.

Not just the RAID, but the recovery (1)

vg30e (779871) | more than 10 years ago | (#9444898)

After building lots of RAID stuff on x86 based machines, I found that whatever RAID you pick for redundancy is probably going to be OK as long as it is more than RAID level 0, but recovery may vary. I would opt for a OS independent solution, where adding new drives doesn't cause you to have to back the whole thing up, and re-initialize the array. Also, it stinks if there are a lot of annoying steps to go through to change a failed drive (reboots etc).

RAID 5 reliability vs RAID 1 reliability (1)

drgreening (594381) | more than 10 years ago | (#9444900)

My sympathies to the author. I had a similar question myself, but simple Googling doesn't really answer the question.

Aren't there some failure modes where RAID 1 doesn't work well? What if a drive doesn't fail, but instead fails to return the correct data?

It seems to me that RAID 5 would determine which of the drives is returning bad data, and correctly mark the drive bad, in situations where RAID 1 might not be able to detect which drive is bad.

Could a RAID expert please address this?

Ugh (1)

CaptainSuperBoy (17170) | more than 10 years ago | (#9444905)

What's best? Probably RAID 0+1 for you. It's striping and mirroring, you gain a good deal of performance, almost double your reliability, and lose 50% of the space.

But geez, what kind of question is this for the front page? Ask on a hardware board or do some reading on your own.

RAID5 (1)

Gareman (618650) | more than 10 years ago | (#9444910)

I'm running Redhat ES3 on my home mail/DNS server using a 3Ware RAID card, Exabyte 3-disk hard drive enclosure, running hardware RAID5. It's easy to set up and manage and provides the best performance vs. fault tolerance. The down side is that the enclosure has a rather loud fan, something you won't be able to avoid with an enclosure.

The noise alternative is probably software raid-1, since you probably don't need extra cooling for only two hard drives. I have this as the configuration of my second server, running Windows 2003.

Re:Which RAID for a Personal Fileserver? (1)

drsmack1 (698392) | more than 10 years ago | (#9444913)

I think that this would be a great "Ask Google" question. Which RAID for a Personal Fileserver? [tinyurl.com]

That said; it was pretty easy in Mandrake 10.0 Official to set up a 3 disk Software RAID 5 with 200Gb disks. Supposedly if one goes bad I can just remove it and put in another one and boot up - regeneration is supposed to be automatic.

what a terrible question to put up (0)

Anonymous Coward | more than 10 years ago | (#9444914)

You sir, should have tried google first, as everyone else said.

That being said, if you've already purchased drives and you have more that two (implied), you'll want to do raid 5. Unfortunately you failed to mention whether you'll be using windows or linux, so we'll have to cover both. In windows, you'll probably want to buy a shitty promise raid card, preferably with 4 or 8 channels (depending on how many drives you have), and set up a software raid with the promise software.
Under linux you'll need a (cheaper) ata controller with as many channels as you have drives, and then you'll want to use google to find out how to install your distro of choice on a software raid you've set up FOLLOWING THE DIRECTIONS GOOGLE FINDS YOU.

Easy (1)

NineNine (235196) | more than 10 years ago | (#9444921)

I use RAID 1 on all of my machines. They don't have the one that I use any mroe, but something like this is only $250 for complete hardware RAID (the best kind). It's absolutely seamless.
http://www.raidexpert.com/RAID/DynaBack er.htm

Question to /. (0, Troll)

tjkrz (653669) | more than 10 years ago | (#9444929)

Can someone do this calculation for me? This seems easier than getting out my graphing calculator. It's all the way inside my bag which is at my feet. 5 * 89 - 303333 + 307 % 4 =

3ware (1)

TheFlu (213162) | more than 10 years ago | (#9444937)

This isn't for personal use, but if I wanted a RAID at home, I would definitely consider the same setup as this:
I'm using the 3ware [3ware.com] 7006-2 on two Linux boxes (Fedora Core 1) and I'm also using one on a Windows 2003 Server as well. All of them are configured with RAID 1 support and I haven't had any issues on any of the machines thus far (knock on wood). I also bought the Vantec EZ-SWAP MRK-102FD Mobile Rack Frame & Carrier for each drive I have in the RAID as well, these things are dirt cheap ($35.00) and are really nice looking with the LCD temperature readout on the front. This setup might be overkill for home use, but it's certainly not terribly expensive either.

Depends (1)

UserChrisCanter4 (464072) | more than 10 years ago | (#9444941)

A lot of people have already pointed out that if you have more than two drives, you should be doing RAID-5. Promise produces a couple of true hardware-level RAID cards in the ~$200-$300 range, depending on how many drives you want, and whether you want IDE or SATA.

3Ware's escalade seems to have much better linux support, but are generally more expensive kit (although many claim they're vastly superior). I have a simple file server that occasionally doubles as a dedicated game server at our monthly LANs, so it has plenty of horsepower, and thus I went with a soft-RAID solution. Highpoint makes a model in the $80 range that implements RAID-5 at the software level, but as long as you have some decent hardware that it's going in, that shouldn't be a huge problem.

Just a few things to remember: if you doing RAID-5, try to have a seperate boot drive so that you can keep swap off of the array disk; swap doesn't need fault tolerance and it will slow you down. If you're planning on using gigabit ethernet and heavily accessing this thing (not sure why in a home situation), look at getting one of the intel 875 or Nforce3 boards that have gigabit on the northbridge, as gigabit and heavy disk access together will saturate your PCI bus. If you only have two discs, ignore all of this, and just mirror them entirely in software.

Raid 1 or Raid 5 (2, Informative)

ed1park (100777) | more than 10 years ago | (#9444942)

Raid 1 for simplicity. 2 drives in mirrored configuration. Cheapest and easiest to setup. Install Linux and use software raid. Works like a charm.

If you're upto a challenge, install Linux to boot from the RAID 1 config. It was a huge pain in the ass to figure out. When I configured Redhat 9, I had to use Lilo instead of Grub as the boot loader wasn't being correctly written for both drives. Had to use "dd" to write the boot sector and Lilo to get it working properly.

Benefits of software raid allow you to swap drives with minimum downtime and recreate the drive in the background. And u save money from not buying a hardware raid card, which could serve as another possible point of failure. Then you can write scripts that can email you the status of the raid periodically with cron.

Remember to test the config by unplugging each drive separately. Of course it will take awhile to sync each drive...

If you are feeling feisty and have more money to spend try this (a copy of a previous post of mine):

Here are some interesting numbers:

$250 per drive
400GB per drive
4 drives
1.2 TB in Raid 5

Total cost $1,000
or $0.83 per MB.

So there you have it. A terabyte file server for about $1000 will be a reality soon enough. Nice. Serial ata will lessen cable clutter, and only 4 drives will be doable in any spare decent case and power supply.

Hopefully it won't take too long for prices to drop to $250.

Of course Raid of any level is no replacement for a full backup, but it's certainly better than nothing or relying on a single drive no matter how good the quality/warranty.

bigger questions, cost of insurance (0)

Anonymous Coward | more than 10 years ago | (#9444945)

RAID does little for you when you have a power problem, either the power supply smokes the mother board, or the drive goes and hozes the IDE interfaces of other drives.
.
I have had both happen.
.
The cheaper solution - is to purchase drives with a good warenty and not the cheapest thing you can find, and a good power supply, not the cheapest one.
.
But the true answer depends on how much you value your time, here - down time at work is about $4000 per hour.
.
What is your time worth for your personal time and trouble?
.
Downtime at home costs what?
.
When will you be upgrading or replacing this? IN 2 years, or 3 years?
.
What is your personal ROI needs?
.
The decision is like buying an insurance policy.

Double Nickle (1)

Ed Almos (584864) | more than 10 years ago | (#9444953)

Here we use the 'double nickle' on all our file servers, RAID 5 spread across five disks. In six years we have never lost data due to a drive failure and if one of the little buggers does die we just pull the drive out of its cage and slot in a new one. The server BIOS (IBM Netfinity) then takes care of rebuilding.

Ed Almos
Budapest, Hungary

RAID 1 for small use only (1)

fayd (143105) | more than 10 years ago | (#9444955)

Generally RAID5 or RAID 10 (not 0+1) is what you'd like to see, but 5 requires a minumum of 3 disks (4 or 5 is better), and 10 requires a minumum of 6 (again, more x2 is better) disks. For personal use, there's just not that much space in the chasis for that many disks. Not to mention the potential cost of acquiring that many disks.

Really, your only choice is RAID1. Two disks, maybe a card (if you don't use the Mobo RAID Controller that seems to be standard these days). For Hardcore (even personal) usage, you're probably better off going with SCSI. However for light use, IDE is fine.

I haven't seen alot on SATA RAID yet, but it seems to be pretty popular. I would imagine it'd be fine for light use as well.

RAID 1 for SOHO (0)

Anonymous Coward | more than 10 years ago | (#9444957)

RAID 1 has another advantage for no one has listed. Make sure to mount your drives on removable trays. In the event of a fire or other disaster, you can just yank out one drive and be confident that you have saved all your data.

No need to burn to a crisp while trying to unplug all the cables going into the PC.

RAID 5 (1)

Mercenary_56 (622604) | more than 10 years ago | (#9444959)

I'm currently running a 3 drive RAID 5. It was pretty easy to get going. It all depends on how much you want to spend and what you want to do with the server. RAID 5 gives you (N - 1)*(drive size) storage (3 x 200GB drives gives you 400 GB storage). The problem with RAID 5 is it requires at least 3 drives, the more the better. I really like my 3ware sata raid card, it gives you the option to have "hot spares" so should it detect a problem, it will automatically start rebuilding onto the spare. It's also a hardware-based card meaning (among other things) it takes very little from the server to rebuild the drive. 3ware's drivers were easy to get running (even in linux) and it included a monitoring system that can send alert emails should something go wrong. For more information on the 3ware cards, check their new line out here [3ware.com]
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