[linux-lvm] pvmove or lv mirror/unmirror

[linux-lvm] pvmove or lv mirror/unmirror

[Carlos Eduardo Tavares Terra]

Dears,

I need to migrate 400GB data from some disks to new disks. The old
disk frame is getting obsolete and will be powered off.

To do this I thought in 3 possibilites:
1. Create a new VG, with new LVs, and CP everything to it. (It'll take
too many time)
2. Include the new disks into the current VG and use pvmove to free
the old disks.
3. Include the new disks into the current VG, convert the LVs to make
use of mirroring, then brake the mirror keeping the new disks as the
running ones.

My doubt is... is it secure to use pvmove in disks with lots of data?
I thought in using mirroring to keep my data safe, until breaking the
mirror. All the syncing would be safer.
This solution will work? What is the best option? May I move, or
mirror, my data in a production environment?

My environment:
HP Blades, connected to SAN disks using FC.
Red Hat 5.2 running Oracle 9.2

Thanks

-- 
Carlos Eduardo Tavares Terra
GNU/Linux #413291 [http://counter.li.org]

Re: [linux-lvm] pvmove or lv mirror/unmirror

[Alasdair G Kergon]

pvmove should work OK, but with a large amount of data you might consider
dividing it into several smaller pvmove commands with the range syntax
  SourcePhysicalVolume[:PE[-PE]...
  /dev/xda:0-100000
to give you more checkpoints along the way.

Alasdair

Re: [linux-lvm] pvmove or lv mirror/unmirror

[James Hawtin]

> My doubt is... is it secure to use pvmove in disks with lots of data?
> I thought in using mirroring to keep my data safe, until breaking the
> mirror. All the syncing would be safer.
> This solution will work? What is the best option? May I move, or
> mirror, my data in a production environment?

I have some pvmovse on 1.5TB sections of data with success, I would warn you
it takes quite some time. Copying anything at the filesystem level takes
longer due to random access, if you want to try that use rsync repeated
times to get things right with minimum down time. DD works well for offline
systems, but you need to set a large block size. 

Like ways though before a bit change make sure you have a backup!

James