On 07/09/2010 10:54 AM, Benjamin Henrion wrote: > On Fri, Jul 9, 2010 at 9:53 AM, Benjamin Henrion <bh@udev.org> wrote: >> Hi, >> >> I have managed to setup an LVM loopback file as a harddisk to mount. >> >> Now, I need the vzdump utility to detect the fact that it is LVM >> based, and it keeps saying that it cannot detect the LVM volume group: >> >> http://openvz.org/pipermail/users/2010-July/003623.html >> >> "unable to detect lvm volume group" >> >> Everything works fine when mount displays that the file is mounted >> with /dev/mapper/mygroup-myvol, on the opposite, it does not work when >> mount outputs /dev/dm-0 in its list. >> >> Any idea how I could force mount to use /dev/mapper/mygroup-myvol >> instead of /dev/dm-0? > As for the "mount", it should be fixed already to handle /dev/dm-X nodes properly and it should resolve the dm-X (internal kernel) name into a real device-mapper name (util-linux-ng >= 2.17). Recent versions of mount should work regardless of the the input that was given initially, /dev/mapper/<real-dm-name> node (symlink) or /dev/dm-X node. > On one machine it creates rightly a device on /dev/mapper: > That's the older layout without udev interfering where the nodes in /dev/mapper are created by device-mapper library directly (this is still supported as a fallback or if udev support is disabled in compile time or while using udev_rules = 0 setting in lvm.conf). > root@buzek /dev/mapper [68]# l > total 0 > crw-rw---- 1 root root 10, 59 2010-07-09 09:32 control > brw-rw---- 1 root disk 254, 0 2010-07-09 10:44 openvzgroup-openvzvol > > While on the other machine where is does not work, it makes a symlink > to /dev/dm-0: > Yes, when udev support is enabled in LVM, the /dev/mapper/<name> is a symlink to /dev/dm-X (this was chosen to comply with udev requirements). > root@chainsaw /dev/mapper [25]# l > total 0 > crw-rw---- 1 root root 10, 59 2010-07-09 10:28 control > lrwxrwxrwx 1 root root 7 2010-07-09 10:46 openvzgroup-openvzvol -> ../dm-0 > > Any idea why this difference? Just different versions of lvm2 involved, I suppose... If there are any other utilities still having problems with the new /dev layout, then they need to be corrected and they need to fix any assumptions about /dev/mapper content. Peter _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
