Mailing List Archive: Linux-HA: Pacemaker

resource dependency

Index | Next | Previous | View Threaded

biancalana at gmail

Nov 20, 2009, 8:42 AM

Post #1 of 6 (510 views)
Permalink

resource dependency

Hi list,

I'm building a 4 node cluster where 2 nodes will export drbd devices
via ietd iscsi target (storage nodes) and other 2 nodes will run xen
vm (app nodes) stored in lvm partition accessed via open-iscsi
initiator, using multipath to failover.

Configuring the cluster resources order I came up with a situation
that I don't find a solution. The xen vm resources depends of iscsi
initiator resource to run, I have two iscsi initiator resources, one
for each storage node, how can I make the vm resources dependent on
any iscsi initiator resources ?

I think in create a clone of the iscsi initiator resource, use rules
to change the clone options in a way that I can have two clones per
app node with different portal parameter. This way I could make the vm
resouces dependency on this clone. Is this possible ?

I'm using debian-lenny with the packages described at
http://www.clusterlabs.org/wiki/Debian_Lenny_HowTo

Excuse me for the bad english.

Best Regards,

Alexandre

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

mpalmer at hezmatt

Nov 20, 2009, 8:53 AM

Post #2 of 6 (487 views)
Permalink

Re: resource dependency [In reply to]

On Fri, Nov 20, 2009 at 02:42:29PM -0200, Alexandre Biancalana wrote:
> I'm building a 4 node cluster where 2 nodes will export drbd devices
> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
> vm (app nodes) stored in lvm partition accessed via open-iscsi
> initiator, using multipath to failover.
>
> Configuring the cluster resources order I came up with a situation
> that I don't find a solution. The xen vm resources depends of iscsi
> initiator resource to run, I have two iscsi initiator resources, one
> for each storage node, how can I make the vm resources dependent on
> any iscsi initiator resources ?

Personally, I think you've got the wrong design. I'd prefer to loosely
couple the storage and VM clusters, with the storage cluster exporting iSCSI
initiators which the VM cluster then attaches to the VMs as required. Put
the error handling for the case where the iSCSI initiator isn't available
for a VM into the resource agent for the VM. To me, this seems like a more
robust solution. Tying everything up together feels like you're asking for
trouble whenever any failover happens -- everything gets recalculated and the
cluster spends the next several minutes jiggling resources around before
everything settles back down again.

- Matt

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

biancalana at gmail

Nov 20, 2009, 9:14 AM

Post #3 of 6 (480 views)
Permalink

Re: resource dependency [In reply to]

On Fri, Nov 20, 2009 at 2:53 PM, Matthew Palmer <mpalmer [at] hezmatt> wrote:
> On Fri, Nov 20, 2009 at 02:42:29PM -0200, Alexandre Biancalana wrote:
>> I'm building a 4 node cluster where 2 nodes will export drbd devices
>> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
>> vm (app nodes) stored in lvm partition accessed via open-iscsi
>> initiator, using multipath to failover.
>>
>> Configuring the cluster resources order I came up with a situation
>> that I don't find a solution. The xen vm resources depends of iscsi
>> initiator resource to run, I have two iscsi initiator resources, one
>> for each storage node, how can I make the vm resources dependent on
>> any iscsi initiator resources ?
>
> Personally, I think you've got the wrong design. I'd prefer to loosely
> couple the storage and VM clusters, with the storage cluster exporting iSCSI
> initiators which the VM cluster then attaches to the VMs as required. Put
> the error handling for the case where the iSCSI initiator isn't available
> for a VM into the resource agent for the VM. To me, this seems like a more
> robust solution. Tying everything up together feels like you're asking for
> trouble whenever any failover happens -- everything gets recalculated and the
> cluster spends the next several minutes jiggling resources around before
> everything settles back down again.

Hi Matt, thank you for the reply.

Ok. But if I go with your suggestion I end with the same question.

Having the 2 node storage cluster exporting the block device via
iSCSI, how can I make the VM resource at the VM cluster depend on
*any* iSCSI target exported ? The standard order configuration just
allow dependency on *one* resource.

The only way I see is configure a ip resource on storage cluster and
use this as portal on iSCSI initiator resource of VM cluster. I don't
want to do this way because I think use multipath, for a quicked
failover.

Alexandre

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

mpalmer at hezmatt

Nov 20, 2009, 9:39 AM

Post #4 of 6 (486 views)
Permalink

Re: resource dependency [In reply to]

On Fri, Nov 20, 2009 at 03:14:16PM -0200, Alexandre Biancalana wrote:
> On Fri, Nov 20, 2009 at 2:53 PM, Matthew Palmer <mpalmer [at] hezmatt> wrote:
> > On Fri, Nov 20, 2009 at 02:42:29PM -0200, Alexandre Biancalana wrote:
> >> ?I'm building a 4 node cluster where 2 nodes will export drbd devices
> >> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
> >> vm (app nodes) stored in lvm partition accessed via open-iscsi
> >> initiator, using multipath to failover.
> >>
> >> ?Configuring the cluster resources order I came up with a situation
> >> that I don't find a solution. The xen vm resources depends of iscsi
> >> initiator resource to run, I have two iscsi initiator resources, one
> >> for each storage node, how can I make the vm resources dependent on
> >> any iscsi initiator resources ?
> >
> > Personally, I think you've got the wrong design. ?I'd prefer to loosely
> > couple the storage and VM clusters, with the storage cluster exporting iSCSI
> > initiators which the VM cluster then attaches to the VMs as required. ?Put
> > the error handling for the case where the iSCSI initiator isn't available
> > for a VM into the resource agent for the VM. ?To me, this seems like a more
> > robust solution. ?Tying everything up together feels like you're asking for
> > trouble whenever any failover happens -- everything gets recalculated and the
> > cluster spends the next several minutes jiggling resources around before
> > everything settles back down again.
>
> Hi Matt, thank you for the reply.
>
> Ok. But if I go with your suggestion I end with the same question.

No, you don't. Whatever you're doing, it's not what I'm suggesting.

> Having the 2 node storage cluster exporting the block device via
> iSCSI, how can I make the VM resource at the VM cluster depend on
> *any* iSCSI target exported ? The standard order configuration just
> allow dependency on *one* resource.

You. Don't. Specify. A. Resource. Dependency. You make your VM RA
handle iSCSI failure internally.

- Matt

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

andrew at beekhof

Nov 20, 2009, 10:35 AM

Post #5 of 6 (473 views)
Permalink

Re: resource dependency [In reply to]

On Fri, Nov 20, 2009 at 5:42 PM, Alexandre Biancalana
<biancalana [at] gmail> wrote:
> Hi list,
>
> I'm building a 4 node cluster where 2 nodes will export drbd devices
> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
> vm (app nodes) stored in lvm partition accessed via open-iscsi
> initiator, using multipath to failover.
>
> Configuring the cluster resources order I came up with a situation
> that I don't find a solution. The xen vm resources depends of iscsi
> initiator resource to run, I have two iscsi initiator resources, one
> for each storage node, how can I make the vm resources dependent on
> any iscsi initiator resources ?

The cluster can't express this case yet.
But its on the to-doo list.

>
> I think in create a clone of the iscsi initiator resource, use rules
> to change the clone options in a way that I can have two clones per
> app node with different portal parameter. This way I could make the vm
> resouces dependency on this clone. Is this possible ?
>
> I'm using debian-lenny with the packages described at
> http://www.clusterlabs.org/wiki/Debian_Lenny_HowTo
>
> Excuse me for the bad english.
>
> Best Regards,
>
> Alexandre
>
> _______________________________________________
> Pacemaker mailing list
> Pacemaker [at] oss
> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

biancalana at gmail

Nov 20, 2009, 11:20 AM

Post #6 of 6 (473 views)
Permalink

Re: resource dependency [In reply to]

On Fri, Nov 20, 2009 at 4:35 PM, Andrew Beekhof <andrew [at] beekhof> wrote:
> On Fri, Nov 20, 2009 at 5:42 PM, Alexandre Biancalana
> <biancalana [at] gmail> wrote:
>> Hi list,
>>
>> I'm building a 4 node cluster where 2 nodes will export drbd devices
>> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
>> vm (app nodes) stored in lvm partition accessed via open-iscsi
>> initiator, using multipath to failover.
>>
>> Configuring the cluster resources order I came up with a situation
>> that I don't find a solution. The xen vm resources depends of iscsi
>> initiator resource to run, I have two iscsi initiator resources, one
>> for each storage node, how can I make the vm resources dependent on
>> any iscsi initiator resources ?
>
> The cluster can't express this case yet.
> But its on the to-doo list.

Thank you for the answer Andrew and congratulations for this great
peace of software.

Best Regards,
Alexandre

_______________________________________________
Pacemaker mailing list
Pacemaker [at] oss
http://oss.clusterlabs.org/mailman/listinfo/pacemaker

Index | Next | Previous | View Threaded

Interested in having your list archived? Contact Gossamer Threads