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Re: xfsdump -s unacceptable performances

To: xfs@xxxxxxxxxxx
Subject: Re: xfsdump -s unacceptable performances
From: "Daniele P." <daniele@xxxxxxxxxxxx>
Date: Wed, 16 Aug 2006 20:05:39 +0200
In-reply-to: <44E349EE.6080905@sgi.com>
Organization: Interline
References: <200608161515.00543.daniele@interline.it> <44E349EE.6080905@sgi.com>
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On Wednesday 16 August 2006 18:38, Bill Kendall wrote:

Hi Bill,
Thanks for the explanations. I only have had a glimpse into the sources.

> And of course there's another scan for dumping the non-dir inodes.
> Keep in mind these are inode scans, which are substantially faster
> than recursing through the directories doing individual stat(2) calls.

Yes, but scanning 10.000.000 inodes when you really need to scan only 4 it's
really a waste of resource.
This is a corner case. But usually I want to backup only 10% of the entire
filesystem.
At this point I have to redesign my backup strategy taking care of
xfsdump strength and weakness.

> Nonetheless, these scans could be optimized by seeking the scan to
> the next inode of interest, which could be found using xfsdump's inomap
> (created in the first scan). This would be beneficial to -s and
> incremental dumps.

That's interesting.

> > Are all there scan really necessary?
>
> A lot of this stuff could be done in a single scan in a disk-to-disk
> backup approach. But in the current scheme, they are necessary.
>
> > Could we expect a performance fix?
> > Is there a workaround?
>
> Nothing is planned, but patches are always welcome.

This too, but for me the xfs filesystem it's a big black box.

Thanks again,
Daniele


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