[Lustre-discuss] MDS activity monitoring

[Andreas Dilger]

On 2011-03-20, at 9:09 PM, Andreas Davour wrote:
> I've decided I want to keep an eye on the activity on my MDS, and poking about 
> in /proc I found both /proc/fs/lustre/mds/<fsname>-MDT0000/stats and 
> /proc/fs/lustre/mdt/MDS/mds/stats which both contain stats about metaops, but 
> while similar they are slightly different. 
> 
> Now, I'm not really sure I see how they are different, and why there are two 
> /proc/fs/lustre/md* directories with stats like that? 

I believe there is actaully a patch in bugzilla that consolidates these two /proc files, and removes one of them.  I think one is just left over for compatibility reasons.

> Can somebody who knows something about lustre internals maybe shed some light 
> on the layout of the /proc files and where to best look to get a grip on what's 
> going on in the file system?

There are two main different types of "stats" files - ones for the network RPC service (e.g. MDS/{mds,mds_readpage}, OSS/{ost,ost_io,ost_create}), and one for the target device (e.g. mds/<fsname>-MDT0000/, obdfilter/<fsname>-OSTnnnn).

Each have slightly different statistics, because they have access to different information.  I think some of this is documented in the manual.

Cheers, Andreas
--
Andreas Dilger 
Principal Engineer
Whamcloud, Inc.