[ovirt-users] Disaster Recovery Testing

[Nir Soffer]

On Wed, Feb 15, 2017 at 2:32 PM, Gary Lloyd <g.lloyd at keele.ac.uk> wrote:
> Hi
>
> We currently use direct lun for our virtual machines and I would like to
> move away from doing this and move onto storage domains.
>
> At the moment we are using an ISCSI SAN and we use on replicas created on
> the SAN for disaster recovery.
>
> As a test I thought I would replicate an existing storage domain's volume
> (via the SAN) and try to mount again as a separate storage domain (This is
> with ovirt 4.06 (cluster mode 3.6))

Why do want to replicate a storage domain and connect to it?

> I can log into the iscsi disk but then nothing gets listed under Storage
> Name / Storage ID (VG Name)
>
>
> Should this be possible or will it not work due the the uids being identical
> ?

Connecting 2 storage domains with same uid will not work. You can use either
the old or the new, but not both at the same time.

Can you explain how replicating the storage domain volume is related to
moving from direct luns to storage domains?

If you want to move from direct lun to storage domain, you need to create
a new disk on the storage domain, and copy the direct lun data to the new
disk.

We don't support this yet, but you can copy manually like this:

1. Find the lv of the new disk

    lvs -o name --select "{IU_<new-disk-uuid>} = lv_tags" vg-name

2. Activate the lv

    lvchange -ay vg-name/lv-name

3. Copy the data from the lun

    qemu-img convert -p -f raw -O raw -t none -T none
/dev/mapper/xxxyyy /dev/vg-name/lv-name

4. Deactivate the disk

    lvchange -an vg-name/lv-name

Nir