This is a tutorial on how to break a mirrored disk, because one of it is faulty in a RAID/array group
After the SAN team has assigned a replacement disk on the server, it is time to break the mirror and add the new PV to the VG. I trust you have taken the necessary steps for a health check, backup and raised a Change Request for the disk replacement
1. First we break the mirrored disk
abyss[/root]# pvchange -a N /dev/dsk/c6t3d0
Warning: Detaching a physical volume reduces the availability of data
within the logical volumes residing on that disk.
Prior to detaching a physical volume or the last available path to it,
verify that there are alternate copies of the data
available on other disks in the volume group.
If necessary, use pvchange(1M) to reverse this operation.
Physical volume "/dev/dsk/c6t3d0" has been successfully changed.
abyss[/root]#
2. We check the PV status and it must be unavailable
abyss[/root]# pvdisplay /dev/dsk/c6t3d0
--- Physical volumes ---
PV Name /dev/dsk/c6t3d0
VG Name /dev/vg01
PV Status unavailable
Allocatable yes
VGDA 2
Cur LV 6
PE Size (Mbytes) 32
Total PE 2170
Free PE 0
Allocated PE 2170
Stale PE 2170
IO Timeout (Seconds) default
Autoswitch On
Proactive Polling On
3. Unattached the faulty disk from disk bay and replace the disk (done onsite by engineer)
4. Once the new disk has been attached, we run the ioscan command to get the new disk name
# ioscan -fnC disk
abyss[/root]# pvcreate /dev/rdsk/c6t3d0
pvcreate: The physical volume "/dev/dsk/c6t3d0" is already recorded in the "/etc/lvmtab" file.
abyss[/root]
5. We then restore the VG and make the PV available to the VG
abyss[/root]# vgcfgrestore -n vg01 /dev/rdsk/c6t3d0
Volume Group configuration has been restored to /dev/rdsk/c6t3d0
abyss[/root]# pvdisplay /dev/dsk/c6t3d0
--- Physical volumes ---
PV Name /dev/dsk/c6t3d0
VG Name /dev/vg01
PV Status unavailable
Allocatable yes
VGDA 2
Cur LV 6
PE Size (Mbytes) 32
Total PE 2170
Free PE 0
Allocated PE 2170
Stale PE 2170
IO Timeout (Seconds) default
Autoswitch On
Proactive Polling On
abyss[/root]# pvchange -a y /dev/dsk/c6t3d0
Physical volume "/dev/dsk/c6t3d0" has been successfully changed.
6. Sync the VG, depending on the size of the VG, sync may take a while. As you can see the number of stale extents keeps reducing
abyss[/root]# vgsync vg01
abyss[/root]# pvdisplay /dev/dsk/c6t3d0
--- Physical volumes ---
PV Name /dev/dsk/c6t3d0
VG Name /dev/vg01
PV Status available
Allocatable yes
VGDA 2
Cur LV 6
PE Size (Mbytes) 32
Total PE 2170
Free PE 0
Allocated PE 2170
Stale PE 2166
IO Timeout (Seconds) default
Autoswitch On
Proactive Polling On
abyss[/root]# pvdisplay -v /dev/dsk/c6t3d0 | grep stale | wc -l
2111
abyss[/root]# pvdisplay -v /dev/dsk/c6t3d0 | grep stale | wc -l
2106
The stale extend will eventually zero out, so run the pvdisplay command to get your final STALE PE reading
The entire process can be done at any time, downtime is not needed. Note that I didn't use the VG deactivate/reactivate commands anywhere in this tutorial. Command tested on HPUX 11.23
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