[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

[linux-lvm] vgscan creation of device nodes for volume groups.



Hi,

I've noticed the following and am wondering about the proper way to handle
this.

I'll try to explain by example, since it's kinda awkward.

I've created 3 volume groups.  vol0, vol1, vol2.  On these I have a
logical volume for each, same names.  Each volume group lives on a
seperate device (pv).  After creation, here's the layout for the /dev/
entries.

[root localhost jweber]# ls -la /dev/vol0
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:21 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:18 ..
crw-r-----    1 root     disk     109,   0 Feb 17 22:15 group
brw-rw----    1 root     disk      58,   0 Feb 17 22:21 vol0
[root localhost jweber]# ls -la /dev/vol1
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:21 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:18 ..
crw-r-----    1 root     disk     109,   1 Feb 17 22:16 group
brw-rw----    1 root     disk      58,   1 Feb 17 22:21 vol1
[root localhost jweber]# ls -la /dev/vol2
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:21 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:18 ..
crw-r-----    1 root     disk     109,   2 Feb 17 22:18 group
brw-rw----    1 root     disk      58,   2 Feb 17 22:21 vol2


Next, I turn all the volumes off and essentially turn off lvm.  I remove
one of the devices (loop devices in this case to test this out).  I'm
removing /dev/loop1 which is the device for /dev/vol1.  I then rerun
vgscan and activate my volumes.  Below are the new /dev entries for the
volumes.

[jweber localhost jweber]$ ls -la /dev/vol0
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:38 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:38 ..
crw-r-----    1 root     disk     109,   0 Feb 17 22:38 group
brw-rw----    1 root     disk      58,   0 Feb 17 22:38 vol0
[jweber localhost jweber]$ ls -la /dev/vol1
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:21 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:38 ..
crw-r-----    1 root     disk     109,   1 Feb 17 22:16 group
brw-rw----    1 root     disk      58,   1 Feb 17 22:21 vol1
[jweber localhost jweber]$ ls -la /dev/vol2
total 40
dr-xr-xr-x    2 root     root         4096 Feb 17 22:38 .
drwxr-xr-x   10 root     root        36864 Feb 17 22:38 ..
crw-r-----    1 root     disk     109,   1 Feb 17 22:38 group
brw-rw----    1 root     disk      58,   1 Feb 17 22:38 vol2
[jweber localhost jweber]$

Note the duplicate device nodes numbers for vol1 and vol2.  This makes
sense in that the prior /dev entry for a volume is left around after
volumes are disable (rather than cleaned up).  Now, the problem I'm having
with this situation is that obviously any entries in /etc/fstab based on
the device node entries may not be proper, I could end up with the wrong
devices mounted on the wrong mount points. ;(

I gather one possible way around this would be to use a filesystem label
on the filesystem on above devices and mount via that.  But last I check,
mount via fslabel didn't work with LVM devices.

Any thoughts on this?  Much appreciated.



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]