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I was told by my datacenter that all HW raid, specifically the LSI 9260-4i hardware RAID controller, does not support SSD TRIM command. My question is, are there severe longevity/speed issues due to this? My datacenter said I would be better off with software RAID, but running software RAID on a 4x256Gb Samsung 830 RAID10 array yielded single drive write-speeds... less than optimal. Finally, does MegaRAID FastPath software address the need for SSD TRIM to some extent?

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The model you mention isn't battery backed-up, which makes it rather useless. I would follow your datacenter's advice and stick to software raid. –  Gabriel Oct 27 '13 at 11:59
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2 Answers

I think TRIM is overrated for the most part. Yes, it can help, if you have a drive that has a heavy random workload (which is mostly the case when you're doing drive benchmarks, or for some other real-world workloads), however most people just don't have those workloads.

Here's an interesting poster from SOSP 11, which was looking at a 'selective TRIM' mechanism but also shows a clear comparison between TRIM on and off. TRIM can have a significant negative impact on your drive performance, and while it does show significant benefit in the long-running postmark test, if this usage pattern doesn't match yours then you can't compare them.

Anandtech covered the Samsung 830, and did look at the effect of TRIM here, however I think you should take most of the tests like the ones mentioned there with a grain of salt. Your workload is very unlikely to be 'torture the drive in the worst possible way for a set period of time and then do my normal job', and so the actual impact of your workload on the drives performance is much harder to understand, as is the benefit of TRIM.

Finally, bear in mind that these SSDs can sustain somewhere north of two orders of magnitude more random IOPS than a spinning drive. Even if you lose half their random performance to TRIM, you still have a system that is fantastically faster than spinning drives.

Personally, I'd ignore the lack of TRIM and go with the hardware RAID controller. I'd also manually overprovision a bit more space on the drive (partition off a bit of space and leave it unused) as overprovisioning helps both workload and endurance. And if it turns out that your workload is a very heavy random-write workload, to be honest, I'd go for better drives anyway :)

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TRIM can impact your speed positively as with prolonged use an SSD can perform worse due to write operations becoming slower and slower due to inefficient writing to certain blocks. TRIM makes sure that the operating system can and will write evenly on all blocks.

So if you don't have TRIM now it could become problematic in the future.

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