Messages in this thread | | | Date | Tue, 19 Jun 2007 11:20:29 -0700 (PDT) | From | david@lang ... | Subject | Re: [ANNOUNCE] Btrfs: a copy on write, snapshotting FS |
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On Tue, 19 Jun 2007, Vladislav Bolkhovitin 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.
David Lang
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