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

[Sunil Mushran]

Repeat the first test. This time run top on the first server. Which
process is eating the cpu? From the time it appears that the second
server is waiting for the AST that the first server is slow to send. And
it could be slow because it may be busy flushing the data to disk.
How much memory/cpu do these servers have?

As far as the second test goes, what is the concurrent write performance
directly to the LV (minus fs).

On Wed, Aug 22, 2007 at 01:14:02PM +0530, Arnold Maderthaner wrote:
> 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.
> 
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