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josephcp

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Reminder since it's a pair of SSDs and most people will probably look into using this for their DB store: If you use current generation controllers/software & SSDs, you're going to have a bad time if you turn on RAID and don't know exactly what you're doing.

TRIM ( https://en.wikipedia.org/wiki/TRIM ) isn't supported with RAID on SSD today on hardware controllers and most distributions of linux don't support TRIM on RAID out of the box if you're doing software RAID, so you're going to see performance plummet like a rock after you do one pass of writes on the disk. In many RAID configurations, you're going to zero-write the entire disk when formatting it, so performance is going to suck from the get-go. For this reason, even if you have a tiny database and don't expect to write 1TB worth of data, your performance might still suck. Personally, I haven't tried linux software md TRIM in production, the patch is pretty recent, so you're on your own here (if possible, scaling out horizontally may be a solution to consider for redundancy, I have no idea what Amazon using for SSDs, but recent Sandforce generations fail all the time, so plan for that).

If you don't know to look for this issue, you're going to be scratching your head when your RAID10 SSD configuration write throughput is worse than a single 7200rpm drive. On the other hand, IOPS on SSDs are AMAZING for databases/datastores. Amazon may have solved this for you already behind their visualization instance, and they might be running their own software striping behind whatever raid you're doing, so be sure to test it out fully first.