On Saturday 09 January 2010, Dipl.-Ing. Michael Niederle wrote: > First thanks alot to Kay and Goffredo! > > But I have another question. > > I read that the current tools cannot display subvolumes, but one should still > be able to mount them. If I try I get an error message: > > > mount -t btrfs -o subvol=root.2010-01-07 /dev/sda3 /save > mount: /dev/sda3 is not a valid block device > > root.2010-01-07 is a snapshot of the /root-directory > > /save is an empty directory used for mounting backups > > taken (successfully) with the following command: > > > btrfsctl -s root.2010-01-07 /root > > What am I doing wrong? Isn't it possible to mount the whole filesystem and a > subvolume at the same time?
It is possible. I do that on my machine. The magic part is that the subvolume/snapshot (are the same thing) has to be under the / of the filesystem. gh...@arakne:/tmp$ mkdir test gh...@arakne:/tmp$ mkdir test-snap gh...@arakne:/tmp$ sudo mount -o /dev/sdc test gh...@arakne:/tmp$ mount | grep btrfs /dev/sdc on /tmp/test type btrfs (rw) gh...@arakne:/tmp$ cd test gh...@arakne:/tmp/test$ sudo mkdir a gh...@arakne:/tmp/test$ sudo btrfsctl -s a/snap-on-subdir . operation complete Btrfs Btrfs v0.19 gh...@arakne:/tmp/test$ sudo btrfsctl -s snap-of-root . operation complete Btrfs Btrfs v0.19 gh...@arakne:/tmp/test$ cd .. gh...@arakne:/tmp$ sudo mount -o subvol=snap-on-subdir /dev/sdc test-snap/ mount: /dev/sdc is not a valid block device gh...@arakne:/tmp$ sudo mount -o subvol=snap-of-root /dev/sdc test-snap/ gh...@arakne:/tmp$ mount | grep btrfs /dev/sdc on /tmp/test type btrfs (rw) /dev/sdc on /tmp/test-snap type btrfs (rw,subvol=snap-of-root) Note: - both the root of the btrfs filesystem and its snapshot are mounted at the same time - if a subvolume/snapshot not placed in the root is mounted an error is returned (/dev/sdX is not a valid block device) > Greetings, Michael Goffredo > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijackATinwind.it> Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
