В Fri, 31 Jul 2015 23:41:44 -0700 Konstantin Svist <fry....@gmail.com> пишет:
> On 07/31/2015 11:12 PM, Andrei Borzenkov wrote: > > [Adding grub-devel for wider discussion] > > > > В Fri, 31 Jul 2015 07:13:03 +0000 > > Konstantin Svist <invalid.nore...@gnu.org> пишет: > > > >> Follow-up Comment #3, bug #39591 (project grub): > >> > >> GRUB_DISABLE_LINUX_UUID=true > >> > >> For some reason I preferred not using UUIDs when setting it up, can't > >> remember > >> why exactly.. > >> > > Is it really possible to mount btrfs if only a single device is given? As I > > understand how multi-device btrfs works, to mount it you need to inform > > kernel about all (or at least enough) components. Today this is normally > > done by scanning each device during boot, feeding it to kernel and asking > > kernel "are there enough devices to attempt mount". This works only with > > UUID due to the way it is implemented in user space (udev+systemd+dracut). > > > > Passing single individual device as root= will defeat this logic - as soon > > as device is present user space will believe everything is OK and will try > > to mount it and likely fails. > > > > IOW - multi-device btrfs must use UUID, at least until something is changed > > in Linux boot device detection logic. > > > > So the only question for me is - should we fail grub-mkconfig in your case > > or ignore GRUB_DISABLE_LINUX_UUID and continue? I tend to fail it with > > clear message. > > > > > Excerpt from > https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices: > > Once you create a multi-device filesystem, you can use any device in the > FS for the mount command: > > mkfs.btrfs /dev/sdb /dev/sdc /dev/sde At which point kernel of course knows all devices that are part of new filesystem. > mount /dev/sde /mnt > bor@opensuse:~/src/systemd> sudo ln -sf /dev/null /run/udev/rules.d/64-btrfs.rules bor@opensuse:~/src/systemd> sudo rmmod btrfs rmmod: ERROR: Module btrfs is not currently loaded bor@opensuse:~/src/systemd> sudo losetup --show -f /tmp/loop0 /dev/loop0 bor@opensuse:~/src/systemd> sudo losetup --show -f /tmp/loop1 /dev/loop1 bor@opensuse:~/src/systemd> sudo blkid ... /dev/loop0: UUID="9e0de080-b2a0-47a8-b9a0-5a3e12fedee2" UUID_SUB="d6f072bb-ce32-4d7b-8cc3-31ef4d15a3d8" TYPE="btrfs" /dev/loop1: UUID="9e0de080-b2a0-47a8-b9a0-5a3e12fedee2" UUID_SUB="e2fb510e-56ed-4a2f-bce4-e53c1387c8b8" TYPE="btrfs" bor@opensuse:~/src/systemd> sudo mount -t btrfs /dev/loop0 /mnt mount: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so. bor@opensuse:~/src/systemd> sudo mount -t btrfs /dev/loop1 /mnt bor@opensuse:~/src/systemd> > IOW, this is normal operation for Btrfs. Maybe not for other RAIDs... > Mounting multi-device btrfs requires explicit cooperation from user space. There is no magic kernel can use to know all other devices. _______________________________________________ Bug-grub mailing list Bug-grub@gnu.org https://lists.gnu.org/mailman/listinfo/bug-grub
