[ovirt-users] Manually moving disks from FC to iSCSI

[Gianluca Cecchi]

On Tue, Jul 11, 2017 at 2:59 PM, Gianluca Cecchi <gianluca.cecchi at gmail.com>
wrote:

> Hello,
> I have a source oVirt environment with storage domain on FC
> I have a destination oVirt environment with storage domain on iSCSI
> The two environments can communicate only via the network of their
> respective hypervisors.
> The source environment, in particular, is almost isolated and I cannot
> attach an export domain to it or something similar.
> So I'm going to plan a direct move through dd of the disks of some VMs
>
> The workflow would be
> On destination create a new VM with same config and same number of disks
> of the same size of corresponding source ones.
> Also I think same allocation policy (thin provision vs preallocated)
> Using lvs -o+lv_tags I can detect the names of my origin and destination
> LVs, corresponding to the disks
> When a VM is powered down, the LV that maps the disk will be not open, so
> I have to force its activation (both on source and on destination)
>
> lvchange --config 'global {use_lvmetad=0}' -ay vgname/lvname
>
> copy source disk with dd through network (I use gzip to limit network
> usage basically...)
> on src_host:
> dd if=/dev/src_vg/src_lv bs=1024k | gzip | ssh dest_host "gunzip | dd
> bs=1024k of=/dev/dest_vg/dest_lv"
>
> deactivate LVs on source and dest
>
> lvchange --config 'global {use_lvmetad=0}' -an vgname/lvname
>
> Try to power on the VM on destination
>
> Some questions:
> - about overall workflow
> - about dd flags, in particular if source disks are thin vs preallocated
>
> Thanks,
> Gianluca
>
>

Some further comments:

- probably better/safe to use SPM hosts for lvchange commands both on
source and target, as this imply metadata manipulation, correct?
- when disks are preallocated, no problems, but when they are thin, I can
be in this situation

source disk defined as 90Gb disk and during time it has expanded up to 50Gb
dest disk at the beginning just after creation will normally be of few GB
(eg 4Gb), so the dd command will fail when fulll...
Does this mean that it will be better to create dest disk as preallocated
anyway or is it safe to run
lvextend -L+50G dest_vg/dest_lv
from command line?
Will oVirt recognize its actual size or what?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ovirt.org/pipermail/users/attachments/20170711/c2cfd0a0/attachment.html>