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On Wed, Aug 10, 2011 at 4:06 PM, Robin H. Johnson <robbat2@g.o> wrote: |
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> On Wed, Aug 10, 2011 at 01:32:12PM +0200, Michał Górny wrote: |
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>> > > That one's udev specific? I guess it could be moved as well. |
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>> > |
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>> > It's a blkid(8) cache to mount stuff by uuid/label and guess FS. |
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>> > Used at least by udev rules and stuff linked against libblkid |
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>> > (fsck.*). Both can be triggered at any time later after boot. |
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>> > blkid(8) can work w/o cache. |
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>> 'Cache' is the key-word here. I suggest pinging upstream |
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>> that /var/cache is there for some reason. |
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> It was historically in /etc because it got used to mount /var. |
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> As an example, if you grab some RHEL systems on the default install, |
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> every entry in the fstab is UUID=... rather than fixed devices. Not |
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> having the cache the mounts will still work, but will be very slow as |
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> all devices will be rescanned. |
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I would think that something like this would change so infrequently as |
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to not matter much. If you're going to actually install new block |
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devices relevant to the boot process, I have to think that somewhere |
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along the lines you'll probably need to mount /etc read-write. |
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mdadm.conf is in a similar boat. So is fstab for that matter (my |
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fstab probably changes more often than the list of permanent block |
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devices does). |
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Note that dracut at least expects to find some of this stuff on /etc. |
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Much of the key stuff gets copied to the initramfs, but dracut |
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actually tries to remount things according to whatever rules it finds |
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in /etc/fstab so that it can respect stuff like noatime, etc. Now, |
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right now that logic only applies to root, since that is all dracut |
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tries to mount right now. |
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Rich |
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