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Re: svn back-end question

From: Sean Laurent <sean_at_neuronfarm.com>
Date: 2005-01-21 00:01:00 CET

On Thursday 20 January 2005 04:32 pm, Steve Greenland wrote:
> On Thu, Jan 20, 2005 at 01:22:06PM -0500, daniel@email.unc.edu wrote:
> > 3. The one concern I have about fsfs is with the number of files in a
> > repository. I have conerns about what happens when there are many
> > thousands of revisions in a repository. Unix filesystems traditionally
> > do not handle that case very well (I'd like to see svn modified to use a
> > hierarchical fsfs repository - no more than 1000 files per directory).
>
<snip>
>
> Hmmm, dir_index is an option that can be set with tune2fs. I'm sure it
> only applies to new directories, but you could probably just create a
> new directory, move the repo files, and then mv the new directory back
> into place, avoiding the backup/restore cycle.)

For those of us who know very little about filesystem level options, could
someone tell us more about dir_index? Reading the tune2fs man page tells me
that the dir_index option tells ext3 to "use hashed b-trees to speed up
lookups in large directories."

How significantly does this speed up lookups? Is there a penalty for lookups
in small directories?

Looking back through the Subversion archives, I only see the one discussion
from last December where dir_index was mentioned. Has anyone done any
testing or comparisons of FSFS with and without dir_index enabled?

-Sean

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Received on Fri Jan 21 00:03:25 2005

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