VGSPLIT - Split LVOLS to Different VG

[Alzhy]

Again .. this shows the major difference between VxVM and LVM...

Only VxVM is the viable solution in this case .. we cannot do it on hardware - EVA Business Copy unless Contiou$ Acce$$ $oftware is purcha$ed. Problem is we're running these operations on rp8420's and SuperDOmes where Full VxVM licenses and maintenance are expensive...

I'll see what management says... as we are already using this approach on HDS (XP Storage) and Solaris 8/9 VxVM.

[Sundar_7]

Forget about my last post. Looks like you cannot execute vgreduce even if the mirror is split.

[Sundar_7]

You can use the following procedure IF you are planning to import the mirror copies on to a DIFFERENT SYSTEM.

This may not be the cleanest method, but the best I could come up with.

1) Mirror the Logical volumes. Here is the trick. The allocation policy for ther logical volumes should be PV strict or PVG-strict. Otherwise, you dont have control over which PV the logical volume will be mirrored to.

It would be a good idea to define all the primary PVs in one PVG, the mirror PVs (that are going to be taken out) as another PVG and mention the allocation policy for the LV as PVG-Strict.

2) Split the LVs. This will create the logical volume device files in the system. By default "b" is appended to the logical volume device file.

Here is the catch

3) After splitting the mirror, you need NOT deactivate the volume group and export the vg IF the mirror copies are to be mounted on a different server

On the target server

a) Create the VG dir, group file
b) Import the VG with only Mirror PVs. These PVs are already part of the VG in the Source system. But that doesnt matter.
c) FSCK and mount the logical volumes.

4) Once you are done with the copies (like backup etc), do a vgchange -a y on the source system and execute lvmerge.

This way there is no downtime involved.

[Duncan Edmonstone]

Hmm - what Sundar is suggesting may well work, but I'll put money on it that if it is put to HP they will say 'not supported', which I suspect given your environment Nelson, may be something you can't do.

VxVM looks like your best and only real option in this scenario.

HTH

Duncan

[Elmar P. Kolkman]

Another solution, by using the fact you can have a volume group on multiple nodes active, but only read-write on one.
After making the splitted mirror, you activate the volume group on all other nodes in read-only mode and then copy the data from the splitted lvol to a read-write lvol to use it.

[Alzhy]

Sundar.. I actually have toyed and tested the idea some months back.. it works, but I would have to agree - HP won't support it if things go wrong..



Thanks all.