xenserver ha improvements
TRANSCRIPT
Cloud Architect & ShapeBlue CTO
Specialise in….
Designing & Building Clouds based on Apache CloudStack / Citrix CloudPlatform
Developing CloudStack training
Blogging and sharing CloudStack knowledge
Involved with CloudStack before donation to Apache
Designed Clouds for Cloudera, Everyware, SunGard, Ascenty, BskyB, Trader Media, M5 Hosting, Team Cymru, Interoute, University of Pennsylvania.…
CloudStack Committer
Who Am I?
How does VM HA work in CloudStack?
VMware – vCenter handles it
XenServer, KVM – CloudStack handles it
Hyper-V – Not currently supported
CloudStack VM HA
Hotfix XS62ESP1004 (and XenServer 6.5.0)
Improved mechanism for detecting a failed Host and electing a new Pool Master
Requires Pool HA to be enabled
Prior to XS62ESP1004, correct procedure was to not enable HA on the XenServer Pool when using with CloudStack
So What's the Problem?
If you dot not setup Pool HA a new Pool Master will NOT be elected in the event of a Pool Master failure
All Hosts in the Cluster will go offline
CloudStack will not trigger VM HA, and will report all VMs as still running
No control of VMs in the affected Cluster
So What's the Problem?
Configure Pool HA but only for the Pool Master and not for VMs
How? Create and mount new SR – must not be used for VMs
Enable Pool HA via UI
XE Commands
Script it
Resolution
Use the UI…
Use the UI…
Use the UI…
Use the UI…
Set ‘Failures tolerated’ to Zero
Use the UI…
Use the UI…
Note: It may take two minutes to enable
HA Enabled
Run following two commands to enable Pool HA
xe sr-list name-label=<SR NAME> --minimal (to get the SR ID)
xe pool-ha-enable heartbeat-sr-uuids=<SR ID>
XE Commands
You will need to disable and re-enable Pool HA as some point in the future, so in true DevOps tradition, if you do it more than once, script it
Create a script called enable-ha.sh on any XenServer and populate with the following :
#!/bin/bash
MGMTHAUUID=`xe sr-list name-label=MGMT-HA --minimal`
xe pool-ha-enable heartbeat-sr-uuids=$MGMTHAUUID
echo "Pool HA is now enabled"
Note the script assumes the SR is called ‘MGMT-HA’
Script it…
To perform a controlled restart of a Pool Master Host: Place into Maintenance Mode within CloudStack
Disable Pool HA
Place the Host into Maintenance Mode with XenCenter to force the promotion of a Slave to Pool Master
Restart the Host
Once Host has fully booted and is online in XenCenter re-enable Pool HA
Exit Maintenance Mode in XenCenter
Exit Maintenance Mode in CloudStack
Managing HA Enabled Pools
