I just received a HP Microserver. I've bought 2 2TB drives and I'm trying to RAID 0 them with the 250GB drive that the microserver comes with. When I RAID the 2 2TB drives together I get 4TB, but if I try and RAID all three, I get 750GB. This doesn't seem logical to me. Could someone explain this for me? Thanks
migrated from stackoverflow.com Jun 25 '12 at 14:34
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The RAID 0 will only take the maximum capacity of the smaller of the disks :
Why ? Because the RAID 0 needs to split each data in 3 and give it to each disk at the same time, increasing the overal I/O speed . Thus, if you were writing the data over 750 GB, 2 chunk of the data could be written on the first 2 disks of 2TB, but there would be no space on the 250GB left for the system to write on it. And No, RAID 0 doesn't handle a multiple size array given if disk space is available (like, from 0 to 750GB, it would write 3x faster, and then, between 750GB and 4250GB it would write 2x faster.
The solution is
(x2, x3 are just theoritical IO perf increase, but it's around that in general)