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On Sat, Oct 31, 2015 at 10:25 AM, Jeremi Piotrowski |
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<jeremi.piotrowski@×××××.com> wrote: |
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> |
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> This is one of the problems with copy-on-write filesystems - they make |
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> disk space accounting more complicated especially with snapshots. |
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Indeed, it is one of the problems with copy-on-write anything. Shared |
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memory is a similar situation - do you count glibc in RAM one time or |
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many? |
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It also gets complicated with compression and dynamic mirroring and |
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such, though at least in these cases a better prediction could |
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probably be made than is often done. |
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Free space usage in these cases really needs to distinguish between |
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shared/exclusive space, but in the case of the former it will probably |
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never be easy to display in a concise manner just what you need to do |
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to reclaim that space. Obviously shared space can only be reclaimed |
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if all its references are deleted. |
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The flip-side of this is that copying data is really cheap. Alias cp |
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to cp --reflink=auto and you can use a copy in many situations where |
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you might have previously used a hard/symbolic link. Obviously all |
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three of those do different things, but before I had reflinks I found |
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myself using hard/symbolic links when they were less than ideal. |
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-- |
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Rich |
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