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Solid State Discs in RAID 0

Community Veteran
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Registered: 04-08-2009

Solid State Discs in RAID 0

Thought I would share this pic of data transfer speeds in my new raid 0 setup - two Intel 520s (240Gb each) - running with Intel's SSD Toolbox and the latest raid drivers. I've never seen speeds like these; about ten times faster than a normal disc drive I would say.
If anyone is thinking about raid-ing SSDs, all I can say is it makes a phenomenal difference.
8 REPLIES
Community Veteran
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Registered: 24-09-2008

Re: Solid State Discs in RAID 0

Thanks for that Nozzer, just migrated my OS and a heavy usage program (Arc 10.1), plus some pretty large datasets (>10GB) that are in constant use to SSD (Samsung 840  - 256 gb), and noticed a phenomenal improvement in performance.
Will now consider a second drive:-
dneill2006
Newbie
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Registered: 28-01-2013

Re: Solid State Discs in RAID 0

Nice speeds, never heard it called a solid state disc though  Huh
SSDs (Solid State Drive) don't have discs like mechanical HDDs do  Wink
VileReynard
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Re: Solid State Discs in RAID 0

It's a good way of halving the expected lifetime of each of your SSD's.
Which is quite expensive.  Grin

Community Veteran
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Re: Solid State Discs in RAID 0

Not so if both the SSD and the raid controller will fully support TRIM, which these do. Since Intel released their Rapid Storage Technology drivers from version 11.7, TRIM has been fully available on their 520 drives in raid if they have the correct firmware.
As you no doubt know, running TRIM will enhance a drive's life. Page relocation (a requirement in SSDs when writing data because data cannot simply be overwritten - something that is not required for standard hard drives, which can overwrite) causes more pages being written inside the SSD as page writes are issued by the host. This is a phenomenon known as write amplification. Write amplification will result in performance degradation on writes (particularly small request, random writes). TRIM reduces this write amplification by increasing spare capacity of the drive. Increased spare capacity allows for more wear leveling which is extremely important for SSDs, because SSD memory cells only have a very limited number of writes. It explicitly tells the SSD's garbage collector where invalid pages are which then erases them. Therefore, TRIM and SSD garbage collection work in tandem for better performance and write amplification reduction (TRIM improves the garbage collector's efficiency).
@Journeys...  if you're going to raid your Samsung SSDs, make doubly sure that TRIM will be supported. I doubt whether it actually will.
VileReynard
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Re: Solid State Discs in RAID 0

I know about TRIM - as a life enhancer.
But doubling your SSD's halves the expected lifetime.
When it fails you lose all data and are left with a broken SSD and a well used SSD.

Community Veteran
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Re: Solid State Discs in RAID 0

On what basis do you say that? The number of read/write operations is identical, just split between both drives. I don't understand how raid would shorten the life of whatever disks are in the array. You're simply accessing the drives normally as far as the drive is concerned; it doesn't "know" it's in a raid array. Maybe you'll end up replacing more disks in the long run, but that's only because you're using two drives at the same time, instead of the one drive setup. The fact that the two SSDs are written to simultaneously doesn't impact the life or reliability of each individual drive, only the total life span of the combined drives, which you have artificially combined into one.  Because of that, and only that, the lifespan of the artificial combined drive will be 50% of a single drive. To put it another way, one single drive may last for five years, two drives in raid may also last for five years as a combined "single" drive. The drawback is increased cost and a slightly increased risk of data loss, but that's the price you pay for an extremely fast setup
And in any case doing a weekly backup will cover your backside against major data loss, and you should ideally do that in any case as even single drives fail sometimes!  Cheesy
VileReynard
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Re: Solid State Discs in RAID 0

A simple MTBF calculation http://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_0 would indicate a shorter life.
However, it all depends on the factors involved in determining the failure rate - probably most important is how many files get striped across both units.

kmilburn
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Registered: 30-07-2007

Re: Solid State Discs in RAID 0

It's not necessarily that any one drive has a shorter life,  but with RAID0,  any drive failure will effectively destroy your data for the entire RAID.
Of all combinations of RAID,  RAID0 is almost as useful as the JBOD configuration.