[Linux-cluster] Virtual ips 'drifting' from one node to another

[Chris Harms]

We went with 2 APC remote power switches.  The ports can be grouped 
together so you can turn off multiple ports at the same time to combat 
redundant power supplies keeping the machine on.  Just remember to have 
the cluster use the same IP address to connect to the APC device for 
each node so they can't both be fenced simultaneously.  The APC software 
only allows one session at a time so the second node will be blocked 
from accessing it on the same IP.

Hope that helps.

Chris

Josh Gray wrote:
> Sorry I'm quite the question asker on the list this week, trying to digest
> the cluster docs pretty quick!
>
> One more Q - Reading the FAQ section on power fencing.  What is the best
> design for a two (or three) node cluster with dual power supplies?  I would
> assume best with regards to redundancy would be two power switches - one for
> each power supply.  But in the case of fencing shoot outs, should they all
> be on the same single switch?  Am I just over thinking this?
>
> " same network path as the path used by CMAN for cluster communication"
> Does that mean literally the same ethernet switch or logical vlan, or what?
>
>
>
>
> #  What is the best two-node network & fencing configuration?
>
> In a two node cluster (where you are using two_node="1" in the cluster
> configuration, and w/o QDisk), there are several considerations you need to
> be aware of:
>
>     * If you are using per-node power management of any sort where the
> device is not shared between cluster nodes, you MUST have all fence devices
> on the same network path as the path used by CMAN for cluster communication.
> Failure to do so can result in both nodes simultaneously fencing each other,
> leaving the entire cluster dead, or end up in a fence loop. Typically, this
> includes all integrated power management solutions (iLO, IPMI, RSA, ERA, IBM
> Blade Center, Egenera Blade Frame, Dell DRAC, etc.), but also includes
> remote power switches (APC, WTI) if the devices are not shared between the
> two nodes.
>     * It is best to use power-type fencing. SAN or SCSI-reservation fencing
> might work, as long as it meets the above requirements. If it does not, you
> should consider using a quorum disk or partition
>
> If you can not meet the above requirements, you can use quorum disk or
> partition.
>
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