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> How does the absense of a read-only file-system affect the ability to |
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> have a union-mount only 'visible' for a specific user or user-process? |
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> Or is this read-only thing necessary to solve another problem? |
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> Essential for the union-mount solution to work, is that it can at |
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> least be *only* visible/available for a given (user) process. Otherwise |
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> your system is less different from a progressive system. Still in that |
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> case, the union-mount solution might have some advantages, like simple |
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> repair, and a backup procedure (unmount the union-mount, or restart the |
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> machine -- assuming you didn't add the union-mount to fstab). |
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The idea seems to be that you have a "live" version of the host system (real |
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"/", which is mounted read-only and unioned with |
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a copy on write system). |
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Current Darwin only allows .dmg or mounting from an unmounted device. In |
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both cases the underlying system is |
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intrinsically read-only, i.e. the union fs is not really needed. |
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I don't think it is a good idea to unomount / remount read-only your root |
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file system. |
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If you clone a existing installation and mount this, I think you have |
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effectively a progressive system. This approach is mentioned in the |
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entoo-macos bootstrap howto. |
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|
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That the union file system is visible to all processes becomes a secondary |
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problem (I think it just means that you could have only one parallel |
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Gentoo union / chroot) |
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|
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The basic problem with the Darwin unionfs implementation is that you have to |
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have a (read-only) file system in the first place, which you can union to. |
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As far as I understand the Linux version (which may be only a wishlist entry |
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resp. a specification, you can do things like |
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mount folder1 read-only U folder2 read-only U folder 3 read-write (where U |
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is a concatenation operator) |
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The FreeBSD soltuins divides these usecases into the actual union (unionfs), |
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and the mount from a subfolder of a mounted deice (nullfs) |
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Regards |
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Dirk |
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-- |
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gentoo-osx@g.o mailing list |