Red Hat ENTERPRISE LINUX 5.1 - LVM ADMINISTRATION Manual page 76

Table of Contents

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

groupfs vg

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

mwi-a- 752.00M

iwi-ao 752.00M

lwi-ao

Attr

LSize

Origin Snap%

-wi-a- 752.00M

VG vg

lvm2 [67.83 GB / 67.10 GB free]

VG vg