Quote:
Originally Posted by photon
With a RAID array, there's something else in between the OS and the actual drive; the RAID controller. So while on a normal drive the OS can see the file system directly, on a RAID drive it can't, it just gives commands to the RAID controller and the RAID controller decides what to do with them.
So in the case of TRIM, part of the process of the command is filling up unused space and then deleting that file again (or something like that, I forget exactly), but to do this it has to have intimate knowledge of the filesystem (the drive itself doesn't know). But with a RAID array the OS doesn't have that intimate knowledge, the RAID controller does.
Eventually RAID controllers will be made that are smart enough to report a spindle speed of 0 to the OS so the OS knows its an SSD, and is smart enough to accept TRIM commands and translate those TRIM commands so they work properly for the SSDs in the array.
SSDs are game changing, but they're still very young and I expect there'll be a lot of challenges like this yet.
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That's why I am still hesitant to adopt them. I was an early Raptor adopter and it only hurt my wallet in the end when I know SSDs can be so much better (and cheaper) only 1 or 2 years down the road.