Messages in this thread | | | Date | Tue, 25 Mar 2008 19:43:06 +0100 | From | Emmanuel Florac <> | Subject | RAID-1 performance under 2.4 and 2.6 |
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I post there because I couldn't find any information about this elsewhere : on the same hardware ( Athlon X2 3500+, 512MB RAM, 2x400 GB Hitachi SATA2 hard drives ) the 2.4 Linux software RAID-1 (tested 2.4.32 and 2.4.36.2, slightly patched to recognize the hardware :p) is way faster than 2.6 ( tested 2.6.17.13, 2.6.18.8, 2.6.22.16, 2.6.24.3) especially for writes. I actually made the test on several different machines (same hard drives though) and it remained consistent across the board, with /mountpoint a software RAID-1. Actually checking disk activity with iostat or vmstat shows clearly a cache effect much more pronounced on 2.4 (i.e. writing goes on much longer in the background) but it doesn't really account for the difference. I've also tested it thru NFS from another machine (Giga ethernet network):
dd if=/dev/zero of=/mountpoint/testfile bs=1M count=1024
kernel 2.4 2.6 2.4 thru NFS 2.6 thru NFS
write 90 MB/s 65 MB/s 70 MB/s 45 MB/s read 90 MB/s 80 MB/s 75 MB/s 65 MB/s
Duh. That's terrible. Does it mean I should stick to (heavily patched...) 2.4 for my file servers or... ? :)
-- -------------------------------------------------- Emmanuel Florac www.intellique.com --------------------------------------------------
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