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