[Ocfs2-users] poor 2 node performance

[Ian Pratt]

Hi,

I've been setting ocfs2 up on a two node 'cluster', using gnbd
(network block device) to talk to a shared disk on a third node.

build/install was very straightforward and I have the file system
mounted on both nodes just fine. However, I've been rather
disappointed by the performance: With just one node actively
using the fs (but with the other mounted) I'm finding that file
system operations are running *very* slowly -- a linux kernel
build takes 5 times longer, with the system blocked on IO most of
the time. 

Looking at the node that is supposedly quiescent, I see that
kernel thread "events/0" is burning 100% of the CPU. Sure enough,
syslog is filling up rapidly with messages of the form:

Oct 17 22:01:13 breakout-0 kernel: process_vote: type: MODIFY, lockid: 2751426560, action: (11) <NULL>, num_ident: 1, alive: 1, write: 0, change2719924224, node=1, seqnum=551559, response=1

I guess I could disable the logging, but, I'm still rather
surprised about the amount of communication between the nodes.
Is this normal?  I guess I was hoping that ocfs2 used some kind
of hierarchical read/write/existence locking on fs subtrees.

Performance with just a single node mounted is perfectly
respectable.

Any suggestions?

Thanks,
Ian