Xenserver pool master server for maintanance

Posted on 2013-12-11
Last Modified: 2013-12-25

I have 3 xen servers in a pool. I am planning to upgraded al 3 server's memory. I planned to do one by one at a time. when i do for pool master (xen1) i will move all vm's into xen2 and xen2, then i will shutdown the pool master and upgrade the RAM and start the pool master server. Is it the right way.

My doubt is, If I down the pool master for memory upgrade, will VM's in other server work?

Question by:kolathaya123
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LVL 23

Accepted Solution

Ayman Bakr earned 500 total points
ID: 39713274
First put your pool master into maintenance mode. Right click on the server, then select Enter Maintenance Mode. Alternatively you can issue the following commands from CLI:
xe host-list

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note down the uuid of the pool master then issue
xe host-disable uuid=<host uuid>
xe host-evacuate uuid=<host uuid>

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The <host uuid> will be the uuid you got from the previous command.

This will automatically migrate the VMs to other servers and trigger an election for another pool master.

After the upgrade and putting it up you need to go out of maintenance mode by right clicking on the server, then selecting Exit Maintenance Mode. Or alternatively issuing this from CLI:
xe host-enable uuid=<host uuid>

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You will do this with the rest of the servers one by one. Hope this helps.

Author Comment

ID: 39713287
Thanks a lot.

One more question.

I don't have full resource to move all vm's into other server's . only 50% of VM's I can move. In this case. first I can shutdown 50% of VM's in the pool master, the put the pool master in maintenance more, so other 50% VM's will move to other hosts and new pool master will be elected right. Then I will switch of pool master, upgrade memory, start pool master, exit maintenance mode.

Is this correct?
LVL 23

Expert Comment

by:Ayman Bakr
ID: 39713300
Yep, you are right. The idea is not to have any VM running on the xenserver you want to bring down. So whether you would like 100% migration, 50% migration or 0% migration of VMs, you need to ensure that the VMs are not running on that XenServer and thus you need to shut down those that are not migrated.

Then when you enter maintenance mode, you are telling the system to disable the XenServer from accepting any VM to start on it, migrate VMs if any exist to other XenServers, and if the XenServer is a pool master, trigger an election for another server to be the pool master.

Next you shut down, do the upgrade, bring it up, test that VMs can start on it, working fine and continue with the rest of the XenServers.
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Author Comment

ID: 39713308
Thank you very much..

Author Comment

ID: 39713493

One more question:

if my pool master is down due to power, I can restore the pool master role to another server in the pool using xe pool-emergency-transition-to-master. But how to bring the VM's from the dead pool master? will they come automatically into the new pool ?
LVL 23

Expert Comment

by:Ayman Bakr
ID: 39713731
The attached file should help you.


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