Red Hat ENTERPRISE LINUX 5 - LOGICAL VOLUME MANAGER ADMINISTRATION Manual page 82

Chapter 6. LVM Troubleshooting
groupfs
100.00 groupfs_mimage_0(0),groupfs_mimage_1(0)
[groupfs_mimage_0] vg
/dev/sda1(0)
[groupfs_mimage_1] vg
/dev/sdb1(0)
[groupfs_mlog]
/dev/sdc1(0)
In this example, the primary leg of the mirror /dev/sda1 fails. Any write activity to the mirrored
volume causes LVM to detect the failed mirror. When this occurs, LVM converts the mirror into a single
linear volume. In this case, to trigger the conversion, we execute a dd command
[root@link-08 ~]# dd if=/dev/zero of=/dev/vg/groupfs count=10
10+0 records in
10+0 records out
You can use the lvs command to verify that the device is now a linear device. Because of the failed
disk, I/O errors occur.
[root@link-08 ~]# lvs -a -o +devices
/dev/sda1: read failed after 0 of 2048 at 0: Input/output error
/dev/sda2: read failed after 0 of 2048 at 0: Input/output error
LV VG Attr
groupfs vg -wi-a- 752.00M
At this point you should still be able to use the logical volume, but there will be no mirror redundancy.
To rebuild the mirrored volume, you replace the broken drive and recreate the physical volume. If you
use the same disk rather than replacing it with a new one, you will see "inconsistent" warnings when
you run the pvcreate command.
[root@link-08 ~]# pvcreate /dev/sda[12]
Physical volume "/dev/sda1" successfully created
Physical volume "/dev/sda2" successfully created
[root@link-08 ~]# pvscan
PV /dev/sdb1
PV /dev/sdb2
PV /dev/sdc1
PV /dev/sdc2
PV /dev/sdd1
PV /dev/sdd2
PV /dev/sde1
PV /dev/sde2
PV /dev/sdf1
PV /dev/sdf2
70
vg mwi-a- 752.00M
iwi-ao 752.00M
iwi-ao 752.00M
vg lwi-ao
LSize Origin Snap%
VG vg lvm2 [67.83 GB / 67.10 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
VG vg lvm2 [67.83 GB / 67.83 GB free]
4.00M i
Move Log Copy%
groupfs_mlog
Devices
/dev/sdb1(0)