On Fri, 09 Apr 2004 22:02:38 +0000, Simon Marchese wrote:

> Tom Van Overbeke wrote:
>> Hi,
>>
>> I have a question about splitlvcopy and chlvcopy:
>>
>> is it correct that splitlvcopy is used to create an independent logical
>> volume based on an existing mirror copy of a logical volume ?
>> actually a conversion of a mirrored copy to a new logical volume.
>> this logical volume has no links anymore with the original logical volume,
>> except the fact that the filesystem on it has the same label as the old one.
>> and there is no way of reusing the new logical volume as a mirror copy of
>> the original logical volume
>>
>> and chlvcopy is used to temporarily break a mirror, to allow one to take a
>> backup of data, and afterwards the copy can be re-attached to the original
>> logical volume and resync'ed.
>>
>> the difference is important to me, because i plan (while doing a migration
>> of data between 2 san's) to do this:
>>
>> a logical volume that is mirrorred on 2 disks, will be cut via the
>> splitlvcopy command. the copy on the second disk will become an independent
>> logical volume. this second disk will be disconnected (via san tools) from
>> the server (and be kept as a 'online' backup).
>> then the original logical volume will be sync'ed to another new disk.
>> if the original logical volume becomes unavailable (because the first disk
>> is corrupt or sth), we will re-connect the second disk to the server, mark
>> the physical disk as active (chpv -va) and be able to use the 'new' logical
>> volume that contains the same data as the original one.
>>
>>
>> everythone still with me ?
>>
>>
>> any input is appreciated.
>>
>> thx,
>> tom.
>>
>>
>
> Yes, the difference is as you describe. However, all the names of the
> LVs get changed (check the manpage and/or try it out). Therefore you
> cannot just "use" them to replace the original ones. Worse, you will
> actually have quorum issues as you have just removed half the volumes in
> a VG. And when you try to use the "removed" disks you will also have
> quorum issues, no matter how you do it.


Hi Simon,

Yes I am aware of the possible quorum issues but these shouldn't be
critical, as there's always the possibility to varyon a volumegroup with
the force option if need be, no ?

regards,

tom.