[Openstack] Using nova-volumes openstack LVM group for other pourposes

Jonathan Proulx jon at csail.mit.edu
Thu Oct 25 15:14:38 UTC 2012


On Thu, Oct 25, 2012 at 12:48:23PM +0200, Daniel Vázquez wrote:
:If we create a volume out of openstack context (it's is not created on
:nova database) only on system level. Can we after add to openstack?
:reformulate ask, Can we add to openstack an existen volumen (it's
:living on nova-volumes group)? I'm not sure on nova-volume create
:command or horizon ... that behavior it will be with existent lv label
:or some other properties.

It would be possible, it would require manually inserting data in many
places though...this definately isn't a supported option but I do
belive it is technically possible

you might need to follow the naming convention (probably should) of
volume-<uuid>, this could be doen with lvrename

you will need to make an entry in the "volumes" table of your nova
database

you will also need an entry in /var/lib/nova/volumes/volume-<uuid> so
that tgtd knows how to map the iSCSI target back to the correct
device.

that's what comes to mind, it's untested and there may be other
pieces, but there isn't anything "special" in the logical volume data
or metadata.

If you're trying to plot a migration path for existing VMs it might be
better to use nova to create a new volume and 'dd' to dump the
contents of the old volume into it just to be sure everthing lines up
correctly.

-Jon

:
:2012/10/24 Daniel Vázquez <daniel2d2art at gmail.com>:
:> Yeah!! Jon, I'm agree with you about organization/separation LVM
:> groups, this is for very very very special situation.
:> Any case if I use nova pattern labeling via logical volumen creation
:> or via renaming label, I hope can switch the content of this custom
:> logical volument to use with openstack, an attach to a VM in future.
:>
:>
:>
:> 2012/10/24 Jonathan Proulx <jon at csail.mit.edu>:
:>> On Wed, Oct 24, 2012 at 08:56:26PM +0200, Daniel Vázquez wrote:
:>> :Hi here!
:>> :
:>> :Can we create and use news logical volumes for own/custom use(out of
:>> :openstack) on nova-volumes openstack LVM group, and use it beside
:>> :openstack operational?
:>> :IMO it's LVM and no problem, but it has openstack collateral consequences?
:>>
:>> If you are talking about creating random logical volumes for
:>> non-openstack use in the same volume group nova-volume or cinder is
:>> using to create volumes (lv are in the same vg but don't otherwise
:>> interact), yes you can do that without ocnfusing openstack or having
:>> your volumes trampled.  For example only having one volume group and
:>> using that for operating system partitions as well as volume-<foo>
:>> volumes for cinder
:>>
:>> I don't think it's a particularly good idea from an organizational
:>> standpoint I'd rather have distinct vg's for each purpose so it is
:>> clear which resources are operating system and which are data, but in
:>> my environment (a private computing/research cloud with a small admin
:>> group and 1k users in a few 10's of closely related tenents) it's
:>> probably more an aesthetic than technical choice.  The larger and more
:>> diverse your situation the stronger I'd argue for keeping them in
:>> seperate VGs.
:>>
:>> -Jon
:
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