I'm running Gentoo kernel 3.3.0 with raid5 on four ICH7 AHCI connected
Seagate 2TB 7200RPM disks. I also have two WD 1TB Green disks in raid1
on a Sil3114 with a JBOD (non-RAID) BIOS.
When I attempt to do a scrub/check on the raid5, the check seems to
proceed without actually reading any data from the disks - the disk
activity lights do not even flicker.
Looking at the speed at which the check completes confirms this:
# cat /proc/sys/dev/raid/speed_limit_min
10000
# cat /proc/sys/dev/raid/speed_limit_max
4000000
# echo check > devices/virtual/block/md0/md/sync_action
# echo check > devices/virtual/block/md127/md/sync_action
...
# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md127 : active raid1 sdf1[1] sde1[0]
976760384 blocks [2/2] [UU]
[>....................] check = 1.7% (17387072/976760384)
finish=380.7min speed=41994K/sec
md0 : active raid5 sdb[1] sda[0] sdd[4] sdc[2]
5860535808 blocks super 1.2 level 5, 512k chunk, algorithm 2
[4/4] [UUUU]
[==================>..] check = 93.9% (1835359616/1953511936)
finish=0.8min speed=2332893K/sec
raid1 runs at about 42MB/s as expected with two WD 1TB Green drives.
raid5 runs at well over 2GB/s - not really possible with four Seagate
2TB 7200RPM drives.
Any ideas on what may be going on there and how to fix it. Let me know
what/if more information may be needed.
Thanks
Peter Urbanec
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