Hello: I'm benchmarking RAID5 Read performance with 4 disks and notice perf drop when using kernel 2.6.27. The perf with 2.6.27 is 150MB/s whereas with kernel 2.6.21 (and same setup), the perf is 180MB/s/ Some of the tests I have done: 1. I ran experiments using iozone also but notice that READ perf with RAID5 in 2.6.27 is ~30% less as compared to 2.6.21. Write perf is similar but Read is an issue. 2. On 2.6.27, I played around with chunk size and blocksize parameters and got ~5% improvement but not much. I used following cmds: #mdadm --create /dev/md0 --level=5 --assume-clean --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd --chunk=32 #mke2fs -b 4096 -E stride=8 /dev/md0 #time dd if=/dev/md0 of=/dev/null bs=94208 count=1024 Is this perf drop a known issue? Can someone please recommend some performance tuning tips? Thanks a lot for your time and help! -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
