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On 17-09-07 at 17:46, Helmut Jarausch wrote: |
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> Hi, |
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Hello, |
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|
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> sorry, this question is not Gentoo specific - but I know there are many |
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> very knowledgeable people on this list. |
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> |
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> I'd like to "hard-link" a file X to Y - i.e. there is no additional |
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> space on disk for Y. |
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> |
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> But, contrary to the "standard" hard-link (ln), file Y should be stored |
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> in a different place (inode) IF it gets modified. |
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> With the standard hard-link, file X is the same as Y, so any changes to |
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> Y are seen in X by definition. |
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|
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> Is this possible |
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> - with an ext4 FS |
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> - or only with a different (which) FS |
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You can use GNU coreutil's `cp --reflink=always'. This will, however, |
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only work on filesystems which support the operation (afaik so far only |
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btrfs). Though other CoW filesystems (such as ZFS) have similar |
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capabilities with snapshotting. |
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The only other possibility I know of would be creating an lvm partition |
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for that file and using lvm snapshots. |
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|
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You should also be able to implement the functionality via fuse on top |
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of an ext4 base if the other solutions aren't to your taste. |
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-- |
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Simon Thelen |
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