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Message-ID: <48B6F69C.3090700@redhat.com> Date: Thu, 28 Aug 2008 15:03:56 -0400 From: Ric Wheeler <rwheeler@...hat.com> To: Theodore Tso <tytso@....edu> CC: Eric Sandeen <sandeen@...hat.com>, ext4 development <linux-ext4@...r.kernel.org>, Ric Wheeler <rwheeler@...hat.com> Subject: Re: Do we need dump for ext4? Theodore Tso wrote: > On Thu, Aug 28, 2008 at 09:58:10AM -0500, Eric Sandeen wrote: > >> I was talking to Ric about dump benchmarks, and he was of the impression >> that dump may not be used that often anymore, at least in the >> enterprise. >> > > Many people don't use the dump/restore any more program any more, > that's definitely true. Whether people use backups (as opposed to > large amounts of RAID) in the enterprise is a different question. I'm > not so sure about the second question. > I think a lot of high end customers still back up to tape (or virtual tape which is basically a tape emulation on top of RAID arrays), but they use commercial programs to do that. > So a couple of comments. First, it's probably not fair to use > different backup programs for the different filesystems. We probably > want to do one set of comparisons where we use tar for all three. > (Note: not all backup/dump programs are doing the right things with > xattr's, so we're not necessarily comparing programs with completely > identical functionality.) > I like Chris's acp program since that is heavily optimized (read files in inode sorted order) and is small enough to tweak. > Secondly, it really wouldn't be hard to update dump/restore for ext4. > It uses libext2fs, so the real problem is that it is explicitly > checking the feature flags. Removing those checks may be all that is > necessary, given that ext2_block_iterate() still works for > extent-based files. I just noted BTW that the dump/restore doesn't > seem to be TOTALLY abandoned. It was last updated in 2006, true, but > there is support for backing up and restoring extended attributes and > ACL's. I wonder if they broke format compatibility with BSD 4.4 > format dump/restore backups when they did it --- and if anyone would > still cares. :-) > > We may as well just time "tar" as an easy baseline. > Finally, I suspect most of the problem with using tar is the HTREE > dirent sorting problem. If we modify tar to sort the directory > entries before emitting the files, and then use that tar across all > the filesystems, I suspect the results would be much more better for > ext3 and ext4. > > - Ted > Like acp ;-) ric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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