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

Sridharan Ramaswamy (srramasw) srramasw at cisco.com
Tue Feb 13 16:43:31 UTC 2007


Thanks Bob. That explains why jindex output didn't change at all while
metadata intensive operations are thrown at gfs.

So I presume there is nothing else that will display whats happening
inside those journal segments. May be I can try to look around in the
code and add more debug log mesg to capture that.

- Sridharan 

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Robert Peterson
> Sent: Tuesday, February 13, 2007 7:17 AM
> To: linux clustering
> Subject: Re: [Linux-cluster] GFS Journaling: How to interpret 
> gfs_tool jindexoutput?
> 
> 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
> 
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