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Phillip Susi wrote: > Right, the kernel does not know how many disks are in the array, so it > can't automatically increase the readahead. I'd say increasing the > readahead manually should solve your throughput issues. Any guesses for a good number? We're in RAID10 (2+2) at the moment on 2.6.8-smp. These are the block numbers I'm getting using bonnie++ : ra wr rd 256 68K 46K 512 67K 59K 640 67K 64K 1024 66K 73K 2048 67K 88K 3072 67K 91K 8192 71K 96K 9216 67K 92K 16384 67K 90K I think we might end up going for 8192. We're still wondering why rd performance is so low - seems to be the same as a single drive. RAID10 should be the same performance as RAID0 over two drives, shouldn't it? Max. > > Max Waterman wrote:>>>> I left the stripe size at the default, which, I believe, is 64K bytes; >> same as your fakeraid below.>>>> I did play with 'blockdev --setra' too.>>>> I noticed it was 256 with a single disk, and, with s/w raid, it >> increased by 256 for each extra disk in the array. IE for the raid 0 >> array with 4 drives, it was 1024.>>>> With h/w raid, however, it did not increase when I added disks. Should >> I use 'blockdev --setra 320' (ie 64 x 5 = 320, since we're now running >> RAID5 on 5 drives)?>>> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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