Re: [linux-lvm] snapshotting to a different volume group

[Stephane Chazelas <stephane.chazelas@emerson.com>]

2008-04-18 10:24:36 +0200, Heinz Mauelshagen:
> On Thu, Apr 17, 2008 at 03:58:09PM +0100, Stephane Chazelas wrote:
[...]
> > is it possible to create a snapshot LV of an original LV
> > but in a different volume group?
> 
> No, not with LVM.

Hi Heinz,

thanks. I've just come accross zumastor while reading the ML
archives. It looks promising for what I'm trying to achieve. I
suspect it's gonna be the same wrt to snapshot though, but I'll
give it a try.

> > or alternatively, what's the best way to bring up a LV in a VG
> > that is missing a PV (as in a disk crash) if that LV has all its
> > extents on still sane PVs?
> 
> vgchange -P -ay

Oh thanks. I missed that as the option was described in lvm(8)
and not in vgchange(8). I'll see how to make it fit in the
initrd scripts.

> If you have 2 disks, you better mirror them to be completely
> HA on the spindle side of things and avoid any such config hassle,
> potentially leaving you with lost data.
[...]

I didn't get that ("the spindle side of things"??). Do you mean
I should mirror the whole disks? Note that they are not the same
size. The thing is I have 400 GB of disk space available, I only
need 100GB of data to be "safe". If I had 2 200GB drives and
wanted to mirror everything, and have 50GB for snapshots, that
would leave me with 150 GB for data. While as I need only 100GB
of safe data and don't need the snapshots to be mirrored. I can
have 250 GB of storage, 150 GB of which I don't care if it's
lost (mirrors and snapshots).

Best regards,
Stephane