jpiszcz

8 x Intel X25-E RAID-0 after ~1 year

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If I'm comparing the right charts, doesn't look like you've lost much over a year. How much data have you written to the drives?

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If I'm comparing the right charts, doesn't look like you've lost much over a year. How much data have you written to the drives?

Correct, I have not filled it up too often, mainly used for iTunes library (10-50GB)..

Keep most of the larger files on a 2TB caviar black.

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If I'm reading that correctly, seq speeds have dropped slightly, but you have gotten a big boost in random transfers over time. Considering those drives haven't had the advantage of TRIM, I'd say thats pretty darn good.

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TRIM is always good; the drive can always make better garbage-collection decisions when it's used. Better garbage collection means less likely that the drive has to do extra work "preserving" chunks of data that aren't needed anymore, when writing other data. But, If you're never "deleting" blocks, then of course that doesn't matter.

The X25-E does pretty aggressive background garbage collection, so in the long term I wouldn't expect too much degradation. The issue is more in terms of immediate degradation after a flurry of writes.

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Without TRIM it doesn't matter whether the "garbage collection" is aggressive. The drive knows nothing about the data it stores and if the drive gets filled the best thing the garbage collection can do is just rearrange the data but it can't free data it don't know anything about.

I'm not sure why the term garbage collection is used. It is quite rare that the drive actually snoops the traffic and sees what the filesystem is doing and makes decisions based on that.

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In my cursory understanding of solid-state drives, all have a pool of unused blocks that aren't included in the stated capacity. TRIM drives additionally have a pool of unused blocks that are part of the stated capacity. When writing data, an unused block is selected to hold the new data, and then the block with the old data is added to the pool of unused blocks. I believe that garbage collection refers to this activity of managing unused (garbage) blocks. So with TRIM and non-TRIM drives, the algorithm is the same, and they both garbage collect. The difference is simply that TRIM has a larger pool of blocks to choose from. Since some blocks result in better performance (for example, only some might already be erased), TRIM performs better. Just a guess, anyway.

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Thats my understandning as well. But I have no idea how that have come to be called garbage collection (especially since there are drives that actually do garbage collecting by checking the content of the file system). And, unfortunately, the algorithm won't affect the long term effects of not having TRIM since it can't do anything about it.

Of course a good algorithm will handle the smaller pool of unused blocks better, but there is no way for it to avoid the available blocks to get used up.

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