[Pacemaker] Fixed! - Re: Problem with dual-PDU fencing node with redundant PSUs

[Lars Marowsky-Bree]

On 2013-07-01T13:52:22, Digimer <lists at alteeve.ca> wrote:

> 1. It won't (reliably) work with DRBD because.

Not by itself, no. You need shared storage for it, not replicated
storage. (Though the shared storage can be provided by other nodes via
iSCSI too.)

> 2. I never trust a fence method that requires the victim be in any way
> operational.

The watchdog integration is hardware-assisted. It's similar to relying
on the hypervisor for fencing, or the management board.

> 3. If I have a SAN, I probably have a SAN switch and can do fabric fencing.

That is not the same. Fabric fencing only cuts the node off from shared
storage; it does not trigger a reboot, nor does it cut the node off from
misbehaving on the network. (Unless you can fence that too, which is
more tricky to setup.)

One of the key advantages is that it is trivial to set up, and works
even on shared storage that doesn't support SCSI(2/3) reservations.

> 4. There is a similar mechanism already in the fence_* world;
> https://alteeve.ca/w/Watchdog_Recovery

Oh, someone reinvented the wheel. Nice ;-)

fence_sanlock though doesn't properly support multiple fencing devices
(sbd supports 1 to 3), and it doesn't offer the additional level of
pacemaker integration that sbd has.


I'm curious; you claim 'fence_sanlock' is a "real fence method", but you
seem to suggest sbd isn't. How is that?


Regards,
    Lars

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Architect Storage/HA
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"Experience is the name everyone gives to their mistakes." -- Oscar Wilde