I get this question at least once every two weeks; Is it possible to handpick a primary node? Until now the answer has always been; No, this is not possible. But is this really the case? Can’t I manually promote a server to primary or demote a server to secondary? Those who have been paying attention might have noticed there’s a way to actually list the current primaries and secondaries from the HA command-line interface.
/opt/vmware/aam/bin/Cli (ftcli on earlier versions) AAM> ln
Now that makes you wonder what else is possible… Lets start with a warning. I don’t know if this is supported. Lets assume it is not. Also keep in mind that the supported limit of primaries is 5, I repeat 5. This is a soft limit, so you can manually add a 6th, but this is not supported. Now here’s the magic…
To promote a node:
/opt/vmware/aam/bin/Cli (ftcli on earlier versions) AAM> promotenode <nodename>
To demote a node:
/opt/vmware/aam/bin/Cli (ftcli on earlier versions) AAM> demotenode <nodename>
Hi Duncan,
In this case, the 6th node will be really considered as primary by others ?
yes it will…
i just test on a big cluster, no more than 6 primary allowed, the others are shuted down
http://x505.free.fr/img/aam-shutdown.jpg
Duncan,
Does manually promoting a host remain a static setting ?
Lets consider a scenario where-in we have 11 hosts spread across 2 sites(Site A and Site B)
Site A : 8 hosts
Site B : 3 Hosts
All the current primaries are at Site A. So as expected if the chassis at Site A looses power, then HA wouldn’t restart the VMs since all the primaries are down.
I am trying to find a way to workaround this problem.
I could think of demoting two primaries at Site A and promoting two secondaries at Site B. But what if we were to do some maintenance in the cluster, will HA re-elect the 2 nodes at site B as primaries ?
Thanks,
Abhilash
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