[Linux-cluster] GFS load average and locking

[Wendy Cheng]

Stanley, Jon wrote:

>2)  The locking statistics seems to be a huge mystery.  The lock total
>doesn't seem to correspond to the number of open files that I have (I
>hope!).  Here's the output of a 'cat /proc/gulm/lockspace - I can't
>imagine that I have 300,000+ files open on this system at this point -
>when are the locks released, or is this even an indication of how many
>locks that are active at the current time?  What does the 'pending'
>number mean?
>  
>

GFS caches locks and normally won't release them (for performance 
reason). However, we do find this could cause latency issue, 
particularly after back up and/or tar command where lots of locks are 
accumulated into one single node that previously issued the backup 
command. Judging by your description of read latency and number of 
"shared" locks in your lockspace output, we do have a new tunable in 
to-be-released-soon RHEL3 Update 7 that allows admin to purge the locks. 
This seems to help several of (beta) customers to resolve their latency 
issues.

Other than this, do you find any error messages in your 
/var/log/messages file ?

-- Wendy