Long term of health of SSDs

MetalX

MetalX

Posts: 1,364   +4
Hello everyone,

I wonder if you guys could answer a few questions about SSDs that I've been sitting on for a while now? Specifically, I'm wondering if SSDs can become "damaged" or permanently altered in performance by getting too full or failing to properly use TRIM. I've got 2 240GB OCZ Agility 3 SSDs in RAID 0 (480GB total size); performance is quite breathtaking and I've seen transfer speeds of ~1GB per second. However, I've heard that TRIM is not supported in Windows 7 (or in general?) when running SSDs in RAID, and I've also read somewhere on the great wide Internet that SSD performance can really drop off as the drives approach full capacity, especially without TRIM functionality. What I have not been able to find any clear information on is whether this performance loss is permanent or if it can be fixed simply by reformatting the drives as another RAID array or as single drives. My Agility 3 RAID array is approximately 69% full as of right now, and it previously was around 82% until I moved some files and apps off of it to my 1TB Caviar Black drive. I could move more apps, but before I do, I'd like to know whether it's even worth the effort.

In short: I'd like to know if A) drive performance has indeed dropped (it doesn't seem like it's dropped too much, but I didn't run any "real" benchmarks on it when it was new so I can't really compare it to anything) and B) if performance has dropped, is there anything I can do to fix it and how would I go about fixing it?

In very short (tl;dr): OCZ 2x240GB Agility 3 RAID 0 Array, will it be slower as it fills? if so, how can it be fixed and is the "damage" permanent?
 
I'll warn you, I don't know that much about SSD's, even though I own one as a boot drive but they are essentially flash memory and as far as I know, the more that is stored on flash memory, the slower it gets (especially in the 90%-100%) full range. I have experienced this with a few smaller devices, especially phones. As far as I know, teh best way is simply to decrease teh data stored on it, or get one with a bigger capacity. Ultimately, this is what I can guess from having expirience with similar types of memory. Hope it helps!
 
The drive is made up of a number of memory chips, which have a finite amount of writes. TRIM works to balance the load evenly across all the chips. If your drive is full, there's less chips left to use for balancing (or, in RAID0 case, it won't do it at all). Therefore, some chips die sooner. This is permanent.
 
St1ckM4n said:
The drive is made up of a number of memory chips, which have a finite amount of writes. TRIM works to balance the load evenly across all the chips. If your drive is full, there's less chips left to use for balancing (or, in RAID0 case, it won't do it at all). Therefore, some chips die sooner. This is permanent.
Click to expand...
RAID0s are known to fail.
 
So since the chips have a finite number of read/write cycles, the wear on them caused by drives that are almost full is permanent, but reformatting the drives will solve the problem of excess wear? Obviously there still will be wear and tear, but read/write cycle use is minimized by keeping open space on the drive, is this correct?
 
It's only write cycles. Formatting the drive and filling it back up but leaving a bit more space will help with wear-levelling, but it won't give you any more write-cycles. You've already used them up.
 
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Ok thanks for clearing that up for me, St1ckM4n. That answers my questions about the SSDs! :) I've been really unclear on those fine details until now.
 
St1ckM4n said:
It's only write cycles. Formatting the drive and filling it back up but leaving a bit more space will help with wear-levelling, but it won't give you any more write-cycles. You've already used them up.
Click to expand...
Wait, so it is basically guaranteed for a SSD to die after the cycles are done? Excuse me I am confused lol
 
You'd fall more under 'average' user category. You'll get at least 10 years out of it, which means it'll outlast every other component in your system.

The three years I mentioned was, like, extreme usage. :p Think enterprise grade programming, database use, etc.
 
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St1ckM4n said:
You'd fall more under 'average' user category. You'll get at least 10 years out of it, which means it'll outlast every other component in your system.

The three years I mentioned was, like, extreme usage. :p Think enterprise grade programming, database use, etc.
Click to expand...
ah lol, you scared me :D
 
Thanks for all the information guys, really helpful stuff! I was worried too about the drives dying after three years, just from what I'd read online, but its nice to know they should last more like 10 years. :)
 
MetalX said:
In very short (tl;dr): OCZ 2x240GB Agility 3 RAID 0 Array, will it be slower as it fills? if so, how can it be fixed and is the "damage" permanent?
Click to expand...

Without TRIM, yes performance will drop without something to remedy but no, damage not permanent. If you have a 256GB SSD and write 200GB per day with a SSD that has a rating of 5000 writes per sector (standard 22nm MLC flash), on paper you will be get 17.5 years. Now that is if you write an average of 200GB a day.

Having said that, 5000 write flash actually in practice has been found to last MUCH longer. Over double that (source - a friend who reviews hardware for a living). I don't have personal experience on write lives - my drives haven't died yet... Just really bad batches last closer to the rating but they are very rare.

The larger the drive you get, the more writes you'll get out of it obviously.
 
St1ckM4n is correct, the damage is permanent. Think about it, if it is called 5000 write flash and lasts (I'll assume your figures are correct) and it fails in 17.5 years that is because the damage IS permanent. You will get more writes out of a larger drive because TRIM will have 'more room' for write leveling, this helps, because the damage is permanent.

Having said that, will I replace my drive before it fails due to obsolescence? Yes. Do I leave half of my SSD boot drive so I can ensure lots of space for wear leveling (I'm being overly cautious, but it's better than leaving 2% free space and yes I know folks who do that on SSD's and Hard Disks) yes I do.

And for UNKNOWN9122, for all intents and purposes EVERY drive you buy is 'guaranteed' to fail, the only thing is when...and it sucks losing data...that's why the bleating...BACK UP your data.
 
Raoul Duke said:
St1ckM4n is correct, the damage is permanent. Think about it, if it is called 5000 write flash and lasts (I'll assume your figures are correct) and it fails in 17.5 years that is because the damage IS permanent. You will get more writes out of a larger drive because TRIM will have 'more room' for write leveling, this helps, because the damage is permanent.
Click to expand...
The 5000 writes limit damage is permanent but not having TRIM is certainly NOT a permanent performance drop. You can always recover that performance loss.
 
Your statement is not clear. Not having the TRIM command means what is called "write amplification" which wears the SSD out prematurely as every write damages. A '5000 write limit' is a statistical figure given at which a certain percentage of the memory fails. That percentage is chosen by the manufacturer. There is nothing here to be "recovered". The only thing is for the required writes to be minimized by the trim command extending the life of the SSD (life extended by writes prevented). eventually the memory the bit is to be written to will fail and the firmware will mark it as not to be written to anymore. When these reach a large number...drive is toast
 
Sorry, getting off topic: what he asked was will his raid 0 array slow as it fills and if so can it be fixed.

From the OCZ FAQ concerning raid 0 arrays and performance "OCZ SSDs feature built-in garbage collection to ensure optimal performance after time, and you can also create an image of your RAID array to be restored following a secure erase of each individual drive. Secure erasing each SSD and then recreating the array will allow for maximum performance."

As far as measuring performance, from the FAQ "To realize the full rated specifications of your drive, OCZ recommends using ATTO32 to test sequential Read/Write speeds, and IOMeter to test the IOPS. OCZ also provides read/write performance metrics using AS-SSD. Some benchmarks perform a large amount of read/writes to the SSD, and we do not recommend excessive benchmarking of your drive."
 
Raoul Duke said:
Your statement is not clear. Not having the TRIM command means what is called "write amplification" which wears the SSD out prematurely as every write damages. A '5000 write limit' is a statistical figure given at which a certain percentage of the memory fails. That percentage is chosen by the manufacturer. There is nothing here to be "recovered". The only thing is for the required writes to be minimized by the trim command extending the life of the SSD (life extended by writes prevented). eventually the memory the bit is to be written to will fail and the firmware will mark it as not to be written to anymore. When these reach a large number...drive is toast
Click to expand...
True you will get write amplification. In theory, under extreme worst case conditions that would reduce writes by a factor of 4x I would say. Actually doing that in practice is something else.

With modern SSDs, many have some remedial feature such as OCZ's garbage collector to recover from not having TRIM.

Also what I meant by the "damage not being permanent", I meant with respect to TRIM, write amp aside, you could apply TRIM to a drive after using it without TRIM to recover FULL performance.
 
Yes, I apologize. When I initially posted my one track mind was thinking only of memory life, while the question was memory life AND performance (pun there, AND, NOR, XOR...lame attempt at computer humor). You are correct, when trim and garbage collection get to do their thing (and they do it when your SSD is on and idle folks...after serious work performance declines, but if you leave the drive on then trim and garbage collection do their work, but the disk must be idle) then the disk recovers its initial performance although I would think at some point near 'end of life' there would be some degredation, but I do not really know. Performance reduction is fully recoverable. So taking the drives out of raid, putting them as ordinary drives allows trim and garbage collection to work, then you put them back into raid 0 with full performance restored. And excessive benchmarking equates to excessive writes which gets back to my first post concerning memory life only. Thanks Darth Shiv I think it's clear now.
 
You guys are great! :) Just the kind of specific details I was looking for, thank you Raoul Duke and Darth Shiv. I really understand what's going on much better now, and understanding helps me decide how to handle this RAID array.
 
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