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Re: xfs_rapair memory requirement per TB

To: "David Chinner" <dgc@xxxxxxx>, "Ralf Gross" <Ralf-Lists@xxxxxxxxxxxx>
Subject: Re: xfs_rapair memory requirement per TB
From: "Barry Naujok" <bnaujok@xxxxxxx>
Date: Thu, 24 Jan 2008 12:26:34 +1100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20080124002828.GC155259@sgi.com>
Organization: SGI
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On Thu, 24 Jan 2008 11:28:28 +1100, David Chinner <dgc@xxxxxxx> wrote:

On Wed, Jan 23, 2008 at 09:53:39AM +0100, Ralf Gross wrote:
Barry Naujok schrieb:
> >
> >Reading the "Repairing a possibly incomplete xfs_growfs command?" thread
> >this month makes me wonder if there is some type of rough formula or
> >guesstimation cheat sheet to figure out how much memory and swap one
> >would need for an xfs_repair given a file system with many terabytes.
> >
> >
> >Say I have an 8TB LUN that needs an xfs_repair. What would be the rough
> >memory requirements and swap space?
> >
> 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:


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.


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