Does ionice work correctly in software-RAID environments? I cannot set the CFQ scheduler for the md devices, because there is no file /sys/block/md0/queue/scheduler . It seems that the scheduler settings for the underlying disks are not propagated to the raid devices.


Code:
$ cat /sys/block/*/queue/scheduler
noop anticipatory deadline [cfq] 
noop anticipatory deadline [cfq] 
none
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noop anticipatory deadline [cfq] 
noop anticipatory deadline [cfq]
Code:
# Now two "dd"s parallel
$ ionice -c3 dd if=/dev/zero of=test1 bs=10M count=100 oflag=dsync
100+0 records in
100+0 records out
1048576000 bytes (1,0 GB) copied, 29,9719 s, 35,0 MB/s
 
$ ionice -c2 -n1 dd if=/dev/zero of=test2 bs=10M count=100 oflag=dsync
100+0 records in
100+0 records out
1048576000 bytes (1,0 GB) copied, 37,251 s, 28,1 MB/s
  
#############
# Or also
$ ionice -c3 dd if=/dev/zero of=test1 bs=14M count=1000
1000+0 records in
1000+0 records out
14680064000 bytes (15 GB) copied, 255,732 s, 57,4 MB/s
 
$ ionice -c2 -n1 dd if=/dev/zero of=test2 bs=14M count=1000
1000+0 records in
1000+0 records out
14680064000 bytes (15 GB) copied, 254,077 s, 57,8 MB/s
Of course I did the two dd's parallel in two seperate terminals.

Any ideas? Thanks,
der Flo