LVM pvs is showing /dev/dm-x as PV name instead of /dev/mapper

n0rus · 08-03-2012, 04:58 PM

Hello folks,

I am having some hard time making LVM's pvs command print /dev/mapper devices instead of dm-X devices.

Extract from lvm.conf:
preferred_names = [ "^/dev/mapper/", "^/dev/[hs]d" ]
filter = [ "a/dev/mapper/.*/", "a/dev/sdb/", "a/dev/sdc/", "r/dev/sd.*/" ]

The weirdest part is that I'm getting /dev/mapper entries when I issue pvscan, but not when I do pvs.

[root@begonia ~]# pvscan
PV /dev/sdc1 VG Volsdc_local lvm2 [135.50 GB / 508.00 MB free]
PV /dev/sdb5 VG Volsda400 lvm2 [46.50 GB / 18.50 GB free]
PV /dev/mapper/new_eva_sandisk1p1 VG NewSanVolEVA01 lvm2 [200.00 GB / 10.00 GB free]
PV /dev/mapper/new_eva_sandisk2p1 VG NewSanVolEVA01 lvm2 [250.00 GB / 5.00 GB free]
PV /dev/mapper/san_disk1 VG san_vg1 lvm2 [450.00 GB / 15.00 GB free]
Total: 5 [1.06 TB] / in use: 5 [1.06 TB] / in no VG: 0 [0 ]

[root@begonia ~]# pvs
PV VG Fmt Attr PSize PFree
/dev/dm-7 san_vg1 lvm2 a- 450.00G 15.00G
/dev/dm-8 NewSanVolEVA01 lvm2 a- 250.00G 5.00G
/dev/dm-9 NewSanVolEVA01 lvm2 a- 200.00G 10.00G
/dev/sdb5 Volsda400 lvm2 a- 46.50G 18.50G
/dev/sdc1 Volsdc_local lvm2 a- 135.50G 508.00M

[root@begonia ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root 10, 63 Aug 4 2012 control
brw-rw---- 1 root disk 253, 6 Aug 3 23:26 new_eva_sandisk1
brw-rw---- 1 root disk 253, 9 Aug 3 23:26 new_eva_sandisk1p1
brw-rw---- 1 root disk 253, 5 Aug 3 23:26 new_eva_sandisk2
brw-rw---- 1 root disk 253, 8 Aug 3 23:26 new_eva_sandisk2p1
brw-rw---- 1 root disk 253, 17 Aug 3 23:26 NewSanVolEVA01-staging
brw-rw---- 1 root disk 253, 11 Aug 3 23:26 NewSanVolEVA01-u01
brw-rw---- 1 root disk 253, 12 Aug 3 23:26 NewSanVolEVA01-u02
brw-rw---- 1 root disk 253, 13 Aug 3 23:26 NewSanVolEVA01-u04
brw-rw---- 1 root disk 253, 14 Aug 3 23:26 NewSanVolEVA01-u06
brw-rw---- 1 root disk 253, 15 Aug 3 23:26 NewSanVolEVA01-u07
brw-rw---- 1 root disk 253, 16 Aug 3 23:26 NewSanVolEVA01-u99
brw-rw---- 1 root disk 253, 7 Aug 3 23:26 san_disk1
brw-rw---- 1 root disk 253, 24 Aug 3 23:26 san_vg1-san_staging
brw-rw---- 1 root disk 253, 18 Aug 3 23:26 san_vg1-san_u01
brw-rw---- 1 root disk 253, 19 Aug 3 23:26 san_vg1-san_u02
brw-rw---- 1 root disk 253, 20 Aug 3 23:26 san_vg1-san_u04
brw-rw---- 1 root disk 253, 21 Aug 3 23:26 san_vg1-san_u06
brw-rw---- 1 root disk 253, 22 Aug 3 23:26 san_vg1-san_u07
brw-rw---- 1 root disk 253, 23 Aug 3 23:26 san_vg1-san_u99
brw-rw---- 1 root disk 253, 0 Aug 4 2012 Volsda400-LogVol00
brw-rw---- 1 root disk 253, 3 Aug 4 2012 Volsda400-LogVol01
brw-rw---- 1 root disk 253, 2 Aug 4 2012 Volsda400-LogVol02
brw-rw---- 1 root disk 253, 1 Aug 4 2012 Volsda400-LogVol03
brw-rw---- 1 root disk 253, 4 Aug 4 2012 Volsda400-LogVol04
brw-rw---- 1 root disk 253, 10 Aug 3 23:26 Volsdc_local-u888

I have read these existing forum topics, but nothing worked for me.
http://www.linuxquestions.org/questi...x-path-754073/
http://www.linuxquestions.org/questi...volume-754741/

What am I doing wrong?

deadeyes · 08-04-2012, 04:16 PM

I actually think you are doing nothing wrong at all

Could you do ls -lh /dev/dm* ?

Note that LVM actually uses dm.
The ls -lh of the dm* devices should confirm this. (if your udev rules keeps them there.)

n0rus · 08-05-2012, 10:27 AM

Thanks for replying.

Actually, I think I found the problem. It seems that "pvdispay", "pvs" and possibly other commands simply ignore the changes you do to lvm.conf. However, "pvscan" is reading the config correctly.

When I disabled caching (write_cache_state = 0), I started getting the PVM names I was after.

deadeyes · 08-05-2012, 12:12 PM

Quote:

Originally Posted by n0rus

Thanks for replying.

Actually, I think I found the problem. It seems that "pvdispay", "pvs" and possibly other commands simply ignore the changes you do to lvm.conf. However, "pvscan" is reading the config correctly.

When I disabled caching (write_cache_state = 0), I started getting the PVM names I was after.

In the end these are symlinks.