On 13/09/2012 05:34, Mathias Buren wrote:
On 13/09/12 11:21, GuoZhong Han wrote:Hi David: I am sorry for last mail that I had not described the requirements of the system very clear. I will detail for you to describe the requirements of the system.(snip)As you said, the performance for write of 16*2T raid5 will be terrible, so what do you think that how many disks to be build to a raid5 will be more appropriate?Personally I wouldn't use more than 5 drives in a RAID5 with drives larger than 1TB, the failure risk is too high. With 16x 2TB drives, how about two RAID6 arrays of 8 drives each, then RAID0 them? (RAID60) Or, two RAID6 arrays with 7 drives each, 2 hotspares, and RAID0 on top. (RAID10 + 2 HSP)
I wouldn't bother with hotspares with RAID6 unless service and replacement of a dead disk is going to take a long time - you already have double redundancy with the raid6. Raid6 on 8 disks is already orders of magnitude safer than raid5 with 16 disks - once you have a higher risk of the power supply taking fire and burning /all/ your disks, you don't benefit from even greater redundancy!
You mention 36 cores. Perhaps you should try the very latest mdadm versions and Linux kernels (perhaps from the MD Linux git tree), and enable the multicore option.
If that is possible for the OP, then that is definitely worth trying. It is this kind of setup that will benefit most from the newer multithreading support.
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