[Linux-cluster] GFS Journaling: How to interpret gfs_tool jindex output?

[Robert Peterson]

Sridharan Ramaswamy (srramasw) wrote:
> I'm trying to measure the usage of journal blocks created within a GFS
> disk. I'm running bonnie++ small file test hoping to overwhelm the
> journal with lot of entries to measure its peak usage. I saw gfs_tool
> prints jindex data structure. Can anyone help to interpret its output?
>  
> Also I like to hear from anyone who went through similar exercise of
> understanding GFS journal usage in an active system.
>  
> thanks,
> Sridharan
Hi Sridharan,

gfs_tool jindex just dumps the journal index file of a GFS file system.
The jindex file is an index of all the journals and where they're located
and the number of segments.  The first part of the output is just a dump
of the jindex file's inode, which doesn't tell you much.
This doesn't tell you much about what's happening inside the actual
journals.

Regards,

Bob Peterson
Red Hat Cluster Suite