mirror/split secondary swap

[Steve Faidley]

While LVM mirroring shouldn't care what it is mirroring/splitting, we are questioning
if we can mirror and split secondary swap.
We are moving from one EMC to another and have a secondary swap on the old one.
They are both connected and we are going to mirror from one to the other then split to the
new one. Has anyone done this with swap partitions?

OLD EMC DISK: c1t1d1
NEW EMC DISK: c2t2d2
/dev/vg02/lvol1 = secondary swap

lvextend ???m 1 /dev/vg02/lvol1 /dev/dsk/c2t2d2
edit /etc/lvmpvg add;

VG /dev/vg02
PVG PVGsplit
/dev/dsk/c1t1d1

lvsplit ???g PVGsplit /dev/vg02/lvol1

I am thinking nothing needs to be done with lvlnboot as it is secondary swap.

Anyone with swap mirror/split/reduce experience please respond.

[James R. Ferguson]

Hi Steve:

I have not, per se, tried what you suggest. However, it would be simpler, I think, to 'lvextend' a *second* mirror copy and once synchronized, 'lvreduce' the *first* mirror copy you no longer want, leaving *one* mirror.

Regards!

...JRF...

[Roger Baptiste]

I agree with the TopGun ;-)
Never tried splitting a mirror
swap before, so the instinct
is to play it safe and use
the lvreduce method, as suggested by James.

-Raj

[Sanjay_6]

Hi Steve,

You can reduce the mirror by doing an "lvreduce -m 0 /dev/vg_name/lv_name /dev/dsk/device_name" and then do and "lvextend -m 1 /dev/vg_name/lv_name /dev/dsk/device_name" to add the mirror to the new path.

Hope this helps.

Regds

[Steve Faidley]

Sorry, I had lvsplit on the mind as that is what we are doing with the other filesystems to preserve them in caase we need to backout (no idea why we would want to backout).
The real point is can you lvextend mirror and lvreduce mirror on a swap lvol on an active system?
Thanks for the replies.

[James R. Ferguson · Accepted solution]

Hi (again) Steve:

There is no reason why you can't 'lvreduce' a secondary swap's mirror and then 'lvextend' it elsewhere. You are not eliminating swap (which *would* require a reboot) so whether or not you have multiple copies should be immaterial.

To 'lvsplit' a logical volume containing swap makes no sense to me. The idea of splitting a mirrored logical volume is to isolate a *static* copy for backup purposes. Swap is certainly not a static entity.

Regards!

...JRF...