When Good Disks Go Bad: Dealing with Disk Failures Under LVM (5900-3153, June 2013)

4. Gathering Information About a Failing Disk

Once you know which disk is failing, you can decide how to deal with it. You can choose to remove

the disk if your system does not need it, or you can choose to replace it. Before deciding on your

course of action, you must gather some information to help guide you through the recovery process.

Is the questionable disk hot-swappable?

This determines whether you must power down your system to replace the disk. If you do not want to

power down your system and the failing disk is not hot-swappable, the best you can do is disable

LVM access to the disk.

Is it the root disk or part of the root volume group?

If the root disk is failing, the replacement process has a few extra steps to set up the boot area; in

addition, you might have to boot from the mirror of the root disk if the primary root disk has failed. If

a failing root disk is not mirrored, you must reinstall to the replacement disk, or recover it from an

Ignite-UX backup.

To determine whether the disk is in the root volume group, enter the lvlnboot command with the –v

option. It lists the disks in the root volume group, and any special volumes configured on them. For

example:

# lvlnboot –v

Boot Definitions for Volume Group /dev/vg00:

Physical Volumes belonging in Root Volume Group:

/dev/dsk/c0t5d0 (0/0/0/3/0.5.0) -- Boot Disk

Boot: lvol1 on: /dev/dsk/c0t5d0

Root: lvol3 on: /dev/dsk/c0t5d0

Swap: lvol2 on: /dev/dsk/c0t5d0

Dump: lvol2 on: /dev/dsk/c0t5d0, 0

What is the hardware path to the disk, LUN instance, LUN hardware path, and LUN

hardware path to the disk?

For the HP-UX 11i v3 release (11.31) and later, when LVM is configured with persistent device files,

run the ioscan command and note the hardware paths of the failed disk. For example:

# ioscan -m lun /dev/disk/disk62

Class I Lun H/W Path Driver S/W State H/W Type Health

Description

======================================================================

disk 62 64000/0xfa00/0x2e esdisk CLAIMED DEVICE online

HP 73.4GST373405FC

0/3/1/0/4/0.0x22000004cf247cb7.0x0

0/3/1/0/4/1.0x21000004cf247cb7.0x0

/dev/disk/disk62 /dev/rdisk/disk62

What recovery strategy do you have for the logical volumes on this disk?

Part of the disk removal or replacement process is based on what recovery strategy you have for the

data on that disk. You can have different strategies (mirroring, restoring from backup, reinitializing

from scratch) for each logical volume.

You can find the list of logical volumes using the disk with the pvdisplay command. For example:

# pvdisplay -v /dev/dsk/c0t5d0 | more

…

--- Distribution of physical volume ---

LV Name LE of LV PE for LV

/dev/vg00/lvol1 75 75