[Ocfs2-users] Slow concurrent actions on the same LVM logical volume

[Arnold Maderthaner]

Hi 2 all !

I have problems with concurrent filesystem actions on a ocfs2
filesystem which is mounted by 2 nodes. OS=RH5ES and OCFS2=1.2.6
F.e.: If I have a LV called testlv which is mounted on /mnt on both
servers and I do a "dd if=/dev/zero of=/mnt/test.a bs=1024
count=1000000" on server 1 and do at the same time a du -hs
/mnt/test.a it takes about 5 seconds for du -hs to execute:
270M    test.a

real    0m3.627s
user    0m0.000s
sys     0m0.002s

or even longer. If i do a du -hs ond a file which is not written by
another server its fast:
977M    test.b

real    0m0.001s
user    0m0.001s
sys     0m0.000s

If I write 2 different files from both servers to the same LV I get
only 2.8mb/sec.
If I write 2 different files from both servers to a different LV
(testlv,test2lv) then I get about 30mb/sec on each write (so 60mb/sec
combined which is very good).
does anyone has an idea what could be wrong. Are there any mount
options for ocfs2 which could help me? is this a lvm2 or ocfs2 problem
(locking,blocking,.... issue) ?

Any help will be appriciated.

yours

Arnold
-- 
Arnold Maderthaner
J4Care Inc.