[Pacemaker] starting a xen-domU depending on available hardware-resources using SysInfo-RA

Dejan Muhamedagic dejanmm at fastmail.fm
Thu Oct 7 13:50:05 UTC 2010 

Hi,

On Thu, Sep 30, 2010 at 08:52:16AM -0400, Vadym Chepkov wrote:
> 
> On Sep 30, 2010, at 2:35 AM, Sascha Reimann wrote:
> 
> > Hi Dejan,
> > 
> > it's working fine with the amount of free ram as the score and a bigger default-resource-stickiness:
> > 
> > primitive v01 ocf:heartbeat:Xen \
> > 	params xmfile="/etc/xen/conf.d/v01.cfg" \
> > 	op monitor interval="30s" timeout="30s" \
> > 	op start interval="0" timeout="60s" \
> > 	op stop interval="0" timeout="40s" allow-migrate="true" \
> > 	meta target-role="Started"
> > primitive v02 ocf:heartbeat:Xen \
> > 	params xmfile="/etc/xen/conf.d/v02.cfg" \
> > 	op monitor interval="30s" timeout="30s" \
> > 	op start interval="0" timeout="60s" \
> > 	op stop interval="0" timeout="40s" allow-migrate="true" \
> > 	meta target-role="Started"
> > primitive v03 ocf:heartbeat:Xen \
> > 	params xmfile="/etc/xen/conf.d/v03.cfg" \
> > 	op monitor interval="30s" timeout="30s" \
> > 	op start interval="0" timeout="60s" \
> > 	op stop interval="0" timeout="40s" allow-migrate="true" \
> > 	meta target-role="Started"
> > location RAM01-v01 v01 \
> > 	rule $id="loc-resv01-rule" ram_free: ram_free gt 6000
> > location RAM01-v02 v02 \
> > 	rule $id="loc-resv02-rule" ram_free: ram_free gt 3000
> > location RAM01-v03 v03 \
> > 	rule $id="RAM01-v03-rule" ram_free: ram_free gt 1000
> > property $id="cib-bootstrap-options" \
> > 	dc-version="1.0.9-74392a28b7f31d7ddc86689598bd23114f58978b" \
> > 	cluster-infrastructure="openais" \
> > 	expected-quorum-votes="4" \
> > 	stonith-enabled="false" \
> > 	default-resource-stickiness="16000" \
> > 	last-lrm-refresh="1285761587"
> > 
> > thanks!
> 
> Hmm, correct me if I am wrong, but these rules won't migrate a VM anywhere unless some dom0 has more then 16000 of ram, no? 
> I don't think this is what you wanted.

The VM won't move elsewhere in case its already running. If it
isn't, then the stickiness doesn't apply and it will go to the
node with most free RAM.

Though I wonder what happens if there's more than one VM that
wants to move simultaneously.

Thanks,

Dejan

> And on a related note, why are there two different SysInfo agents? Which one is supported?
> 
> /usr/lib/ocf/resource.d/heartbeat/SysInfo
> /usr/lib/ocf/resource.d/pacemaker/SysInfo
> 
> Thanks,
> Vadym
> 
> > 
> > On 09/28/2010 12:18 PM, Dejan Muhamedagic wrote:
> >> Hi,
> >> 
> >> On Tue, Sep 28, 2010 at 11:00:18AM +0200, Sascha Reimann wrote:
> >>> howdy!
> >>> 
> >>> I'm trying to configure a resource (xen-domU) that could start on 2
> >>> nodes (preferred on node server01):
> >>> 
> >>> primitive v01 ocf:heartbeat:Xen \
> >>> 	params xmfile="/etc/xen/conf.d/v01.cfg" allow-migrate="true"
> >>> location loc-v01p v01 200: server01
> >>> location loc-v01s v01 100: server02
> >>> 
> >>> That's working fine so far, but I want to ensure that there's enough
> >>> hardwareresources available on server01, so I've set up a modified
> >>> SysInfo-RA to put the ram_total and ram_free values of xen (xm
> >>> info|awk '/free_memory/ {print $3}') to the statusinformation of the
> >>> CIB:
> >>> 
> >>> server01:~$ cibadmin -Q -o status|grep status-server01-ram
> >>> <nvpair id="status-server01-ram_total" name="ram_total" value="8191"/>
> >>> <nvpair id="status-server01-ram_free" name="ram_free" value="2000"/>
> >>> 
> >>> This is working fine, too. BUT:
> >>> 
> >>> When I create a rule like the one below, the xen-domU keeps
> >>> restarting (or moving to server02 where the same happens), which is
> >>> correct since the SysInfo-RA updates the statusinformation to
> >>> value="0" after a start and back to value="2000" after a stop in
> >>> this example.
> >>> 
> >>> location loc-resv01 v01 \
> >>> 	rule $id="loc-resv01-rule" -inf: ram_free lt 2000
> >> 
> >> An interesting issue :-)
> >> 
> >> Well, you can introduce resource stickiness and use that to
> >> outweigh the negative score coming from the lack of memory (use
> >> something less than inf). You may also consider using the amount
> >> of free memory as a score.
> >> 
> >> HTH,
> >> 
> >> Dejan
> >> 
> >>> Can anybody help?
> >>> 
> >>> _______________________________________________
> >>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
> >>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
> >>> 
> >>> Project Home: http://www.clusterlabs.org
> >>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> >>> Bugs: http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
> > 
> > 
> > -- 
> > Für weitere Fragen stehen wir Ihnen gerne zur Verfügung.
> > 
> > Mit freundlichen Grüßen
> > 
> > Sascha Reimann
> > 
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> 
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