Open Stack

On Sun, Jan 18, 2015 at 11:41 PM, Amit Das <amit.das at cloudbyte.com> wrote:
> Hi John,
>
>>
>> Otherwise you can move to multibackend but you will need to update the
>> hosts column on your existing volumes.
>
>
> For above statement, did you mean a unique backend on separate volume nodes
> ?
>
> Will there be any issues, if the enabled_backends are used with each backend
> tied to particular volume type. Now this configuration is repeated for all
> volume nodes. Do we need to be concerned about the host entry ?
>
>
> Regards,
> Amit
> CloudByte Inc.
>
> On Mon, Jan 19, 2015 at 4:14 AM, John Griffith <john.griffith at solidfire.com>
> wrote:
>>
>>
>> On Jan 16, 2015 9:03 PM, "mad Engineer" <themadengin33r at gmail.com> wrote:
>> >
>> > Hello All,
>> >               i am working on integrating VNX with cinder,i have plan
>> > to add another NFS storage in the future,without removing VNX.
>> >
>> > Can i add another backend while first backend is running without
>> > causing problem to running volumes.
>> > I heard that multiple backend is supported,
>> >
>> > thanks for any help
>> >
>> > _______________________________________________
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>> > Post to     : openstack at lists.openstack.org
>> > Unsubscribe :
>> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
>>
>> So as long as you used the "enabled backend" format in your existing
>> config you "should" be able to just add another backend without impacting
>> your existing setup (I've never tried this with NFS/VNX myself though).
>>
>> If you're not using the enabled backends directive you can deploy a new
>> cinder - volume node and just add your new driver that way.
>>
>> Otherwise you can move to multibackend but you will need to update the
>> hosts column on your existing volumes.
>>
>>
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>>
>

Hi Amit,

My point was that the way multi-backend works is by the addition of
the "enabled_backends" parameter in the cinder.conf file, along with a
driver section:

    enabled_backends = lvm1,lvm2
    [lvm1]
    <driver settings>
    [lvm2]
    <driver settings>

This will cause your host entry to be of the form:
<cinder-vol-node-name>@<backend-name>

In this scenario you can simply add another entry for enabled_backends
and it's corresponding driver info entry.

If you do NOT have multi backend setup your host entry will just be:
<cinder-vol-node-name> and it's a bit more difficult to convert to
multi-backend.  You have two options:
1. Just deploy another cinder-volume node (skip multi-backend)
2. Convert existing setup to multi-backend (this will require
modification/update of the host entry of your existing volumes)

This all might be a bit more clear if you try it yourself in a
devstack deployment.  Give us a shout on IRC at openstack-cinder if
you get hung up.

Thanks,
John