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Date: Wed, 20 Jun 2007 12:41:00 +0400 From: Vladislav Bolkhovitin <vst@...b.net> To: david@...g.hm Cc: Pádraig Brady <P@...igBrady.com>, Chris Mason <chris.mason@...cle.com>, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: Re: [ANNOUNCE] Btrfs: a copy on write, snapshotting FS david@...g.hm wrote: >>> > 3. De-de-duplicate blocks on disk, i.e. copy them on write >>> > > I suppose that de-duplication itself would be done by some user >>> space >>> > process that would scan files, determine blocks with the same data and >>> > then de-duplicate them by using syscall or IOCTL (2). >>> > > That would be very usable feature, which in most cases would >>> allow to >>> > shrink occupied disk space on 50-90%. >>> >>> Have you references for this number? >> >> >> No, I've seen it somewhere and it well confirms with my own observations. >> >>> In my experience one gets a lot of benefit from >>> the much simpler process of "de-duplication" of files. >> >> >> Yes, sure, de-duplication on files level brings its benefits, but on >> FS blocks level it would bring ever more benefits, because there are >> many more or less big files, which are different as a whole, but with >> a lot of the same blocks. Simple example of such files is UNIX-style >> mail boxes on a mail server. > > > unix style mail boxes would not be a good example of wins for > sector-based de-duplication since the duplicate mail is not going to be > sector aligned. Yes, I realized that after I sent the e-mail. Handling of the same, but not aligned, data in different files would need more complex logic. Maybe too complex. Vlad - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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