RE: Mirrored disk but not same PE ?

[Charles Ooi Chia Lun]

Dear Sir,
We got a weird scenario here, we got a system that have mirrorred the 2 disks but doesn't same size PE found. How to troubleshoot these? thank you a lot.

[Sundar_7]

Sorry, the question is not clear.

PE size is defined at the VG level, not at the PV level. So once you create a VG and add the PVs to the VG, the PE size is the same for all the PVs.

[A. Clay Stephenson]

I assume that we are talking about LVM. All the physical volumes (PV's -> disks, LUN's) within a VG must have the same PE size. Therefore, if you are seeing different PE sizes then these PV's must belong to different VG's. You should also note that mirroring does not occur at the disk level but rather at the LVOL level.

[James R. Ferguson]

HI Charles:

It would be easist if you post what you are looking at.

Remember, however, that mirroring is done at the *LOGICAL VOLUME* level. Thus you should use :

# lvdisplay -v /dev/vgNN/lvolX

...to see the state and number of your mirrored extents.

If you are looking at the output from:

# vgdisplay -v vgNN

...then it is very possible that the PHYSICAL volumes comprising the volume group are of slightly different sizes (in terms of number of physical extents). This is meaningless.

Regards!

...JRF...

[Granite]

Hi Charles,

It cant be possible of having diff. PE(size)in a single VG. As it is obvious that, once the second disk is added to the VG for mirroring its PE size will be defined automatically as same as defined for that VG.You cant change after that unless you scratch that VG.

You can post your vgdisplay o/p better.

regds, Granite