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List: ext3-users
Subject: Re: ext3 usage guidance
From: "T. Horsnell" <tsh () mrc-lmb ! cam ! ac ! uk>
Date: 2007-03-29 10:09:07
Message-ID: 20070329100907.GA7238 () ls1 ! lmb ! internal
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On Thu, Mar 29, 2007 at 03:16:44AM -0600, Andreas Dilger wrote:
> On Mar 28, 2007 18:47 +0100, T. Horsnell wrote:
> > 1. The effect on performance of large numbers of (generally) small files
> > One of my ext3 filesystems has 750K files on a 36GB disk, and
> > backup with tar takes forever. Even 'find /fs -type f -ls'
> > to establish ownership of the various files takes some hours.
> > Are there thresholds for #files-per-directory or #total-files-per-filesystem
> > beyond which performance degrades rapidly?
>
> You should enable directory indexing if you have > 5000 file directories,
> then index the directories. "tune2fs -O dir_index /dev/XXX; e2fsck -fD /dev/XXX"
Thanks very much.
Do you mean '> 5000 directories-per-filesystem' or '> 5000 files-per-directory' ?
tune2fs refers to 'large directories' which implies to me that its files-per-directory
Cheers,
Terry.
>
> > 2. I have a number of filesystems on SCSI disks which I would
> > like to fsck on demand, rather than have an unscheduled
> > fsck at reboot because some mount-count has expired.
> > I use 'tune2fs -c 0 and -t 0' to do this, and would like
> > to use 'shutdown -F -r 'at a chosen time to force fsck on
> > reboot, and I'd then like fsck to do things in parallel.
> > What are the resources (memory etc) required for parallel
> > fsck'ing? Can I reasonably expect to be able to fsck say,
> > 50 300GB filesystems in parallel, or should I group them into
> > smaller groups? How small?
>
> I think it was at least "(inodes_count * 7 + blocks_count * 3) / 8" per
> filesystem when I last checked, but I don't recall exactly anymore.
>
> Cheers, Andreas
> --
> Andreas Dilger
> Principal Software Engineer
> Cluster File Systems, Inc.
>
--
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