[Ocfs2-users] read/write performance across cluster

[Florin Andrei]

Red Hat 5 kernel 64 bit, OCFS2 1.4.4.

Two servers with lots of RAM, filesystem is on a SAN via Fiber Channel, 
the Ethernet between servers is pretty fast.

There's a volume on the SAN used for logs. A log collector runs on one 
server, appending lines to a variety of log files in real time. The same 
filesystem is mounted on the other server via OCFS2.

Now here's the thing: if I grep the log files on the same system that 
appends data to the log files, grep is fast. If I grep the logs on the 
other system, it's slower. Depending on the situation, it can be MUCH 
slower, many orders of magnitude slower.

Is this some kind of file locking issue?

I expected the performance to be somewhat different. After all, if I run 
grep on the system that is also writing to the logs, the files are fresh 
in RAM, so it must be fast. But I was surprised by how much slower grep 
is on the other system. This doesn't feel right. Both systems are on the 
same fast LAN, the SAN is fast, etc.

Any suggestions?

-- 
Florin Andrei
http://florin.myip.org/