Subject: Re: xfs_rapair memory requirement per TB
From: Rene Salmon <salmr0@bp.com>
To: Barry Naujok <bnaujok@sgi.com>
Cc: David Chinner <dgc@sgi.com>, Ralf Gross <Ralf-Lists@ralfgross.de>,
        xfs@oss.sgi.com
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Date: Thu, 24 Jan 2008 09:50:16 -0600
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> >> >
> >> > General rule of thumb at the moment is 128MB of RAM/TB of
> filesystem
> >> > plus 4MB/million inodes on that filesystem.
> >>
> >> Did this change lately? I found the rule of thumb: 2 GB RAM for 1
> TB
> >> of disk storage + some RAM per x inodes.
> >
> > The above is based on actual theoretical usage, the below:
> >
> >> http://oss.sgi.com/archives/xfs/2005-08/msg00045.html
> >
> > was based on reported usage on during live repair runs.
> >
> > I think Barry discovered the difference to be things external
> > to repair such as heap fragmentation and has since corrected
> > the worst of the issues so requirements are, in general,
> > much closer to the theoretical numbers now.
> 
> Yes, quite a few memory improvements have been made.
> 
> Right now, I can repair a 9TB filesystem with ~150 million inodes
> in 2GB of RAM without going to swap using xfs_repair 2.9.4 and
> with no custom/tuning/config options.


Thanks. That is great news about the memory improvements.  We currently
run SLES 10 SP1 which comes with:

hpcxe005:# xfs_repair -V
xfs_repair version 2.8.16

others come with:

hpcxe001:~ # xfs_repair -V
xfs_repair version 2.9.2


Did the memory improvements make it into 2.8.16? How about 2.9.2? If not
i take it we can download the latest source and just have the 2.9.4
xfs_repair binary laying around in case we ever need to use it.  Would
using a 2.9.4 xfs_repair binary on a 2.8.16 created xfs file system
cause any problems?

Thanks
Rene

>