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Am Fri, 15 Sep 2017 14:28:49 -0400 |
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schrieb Rich Freeman <rich0@g.o>: |
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> On Fri, Sep 8, 2017 at 3:16 PM, Kai Krakow <hurikhan77@×××××.com> |
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> wrote: |
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> > |
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> > At least in btrfs there's also a caveat that the original extents |
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> > may not actually be split and the split extents share parts of the |
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> > original extent. That means, if you delete the original later, the |
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> > copy will occupy more space than expected until you defragment the |
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> > file: |
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> |
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> True, but keep in mind that this applies in general in btrfs to any |
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> kind of modification to a file. If you modify 1MB in the middle of a |
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> 10GB file on ext4 you end up it taking up 10GB of space. If you do |
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> the same thing in btrfs you'll probably end up with the file taking up |
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> 10.001GB. Since btrfs doesn't overwrite files in-place it will |
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> typically allocate a new extent for the additional 1MB, and the |
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> original content at that position within the file is still on disk in |
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> the original extent. It works a bit like a log-based filesystem in |
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> this regard (which is also effectively copy on write). |
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Good point, this makes sense. I never thought about that. |
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But I guess that btrfs doesn't use 10G sized extents? And I also guess, |
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this is where autodefrag jumps in. |
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-- |
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Regards, |
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Kai |
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Replies to list-only preferred. |
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