Cross-device link on Volume Groups using EMC BCV's

[Chris Lonergan_1]

Setup:-

HP T600 connected to EMC array with STD & BCV devices

Active volume group on BCV devices

Procedure:-

1. De-activate volume group
2. Establish BCV devices
3. Split BCV devices
4. Activate volume group as read only

Problem:-

1. Cross-device link error on all PVs within volume group.

Volume group fails to activate as devices cannot be accessed and
therefor quorum not present.

Workaround:-

Export & Re-import volume group allows VG to be activated.

Question:-

There are several systems with the setup as above, all at the same patch
level, but the problem does not occur on all of them. Why is this ?

/etc/lvmtab is fine. The VG's are not activated on any other system.

[Markus Vogt]

Chris,

do your disk drives have duplicate paths (alternate
links) associated with them, so that each disk drive
can be reached via two different device files?
If that is the case, you might want to verify, that
the two device files are not being used by different
volume groups at the same time.
Basically, it seems that two volume groups might be
'competing' for the same physical disk...

- Markus

[Aaron Nienhuis_1]

If the BCV VG is on the same host as the standard VG, you need to make sure you
vgexport and vgimport the volume group after every sync and split of the BCV
devices. Once you establish a BCV mirror with the standard, all the LVM
headers on the BCV devices are changed to be mirrors of the standard devices.
When the devices are split, the devices must be vgimported into a new VG. If
the BCV devices are going to be activated on the same host as the standard
devices, the VG ID must be changed on all the devices before they can be
vgimported (see vgchgid).

Aaron