[pve-devel] UUID for VM's and disks

[Andrew Thrift]

Hi Dietmar,

Using a pool per cluster will mean that you may need to split/shrink
your placement group count to stay within Ceph best-practises.  With
using a fixed number of pools, you can calculate the correct number of
PG's for your estimated OSD count.
By using a UUID for the disks and having a shared ceph pool, we would
be able to move VM's between the PVE clusters to balance around the
Proxmox clustering limits without fear of overlapping disk ID's.


Having UUID's for VM's is not as important, but just ensures that 3rd
party applications are referencing a unique ID for a VM and removes
the potential for basic coding errors removing a VM from the wrong
cluster.



On Mon, May 16, 2016 at 5:08 PM, Dietmar Maurer <dietmar at proxmox.com> wrote:
>> The use of VMID's for disks is becoming an issue for us with Ceph.  We
>> cannot have multiple PVE clusters sharing the same pool on Ceph as
>> there will be duplicate VMID's across the clusters that will result in
>> a clash of RBD names on Ceph.  I am sure this would be an issue with
>> iSCSI+ZFS as well.
>
> The suggestion is to use different pools.
>
>
>> Using UUID's for VM's would have benefits when using an external
>> application to manage multiple PVE clusters.
>
> Why? What application do you talk about exactly?
>
>