On 4/8/21 8:16 AM, Reid Wahl wrote:
On Wed, Apr 7, 2021 at 9:46 PM Strahil Nikolov <hunter86...@yahoo.com
<mailto:hunter86...@yahoo.com>> wrote:
I always though that the setup is the same, just the node count is
only one.
I guess you need pcs, corosync + pacemaker.
If RH is going to support it, they will require fencing. Most
probably sbd or ipmi are the best candidates.
I don't think we do require fencing for single-node clusters. (Anyone
at Red Hat, feel free to comment.) I vaguely recall an internal
mailing list or IRC conversation where we discussed this months ago,
but I can't find it now. I've also checked our support policies
documentation, and it's not mentioned in the "cluster size" doc or the
"fencing" doc.
The closest thing I can find is the following, from the cluster size
doc[1]:
~~~
RHEL 8.2 and later: Support for 1 or more nodes
* Single node clusters do not support DLM and GFS2 filesystems (as
they require fencing).
~~~
To me that suggests that fencing isn't required in a single-node
cluster. Maybe sbd could work (I haven't thought it through), but
conventional power fencing (e.g., fence_ipmilan) wouldn't. That's
because most conventional power fencing agents require sending a
"power on" signal after the "power off" is complete.
And moreover you have to be alive enough to kick off
conventional power fencing to self-fence ;-)
With sbd the hardware-watchdog should kick in.
Klaus
[1] https://access.redhat.com/articles/3069031
<https://access.redhat.com/articles/3069031>
Best Regards,
Strahil Nikolov
On Thu, Apr 8, 2021 at 6:52, d tbsky
<tbs...@gmail.com <mailto:tbs...@gmail.com>> wrote:
Hi:
I found RHEL 8.2 support single node cluster now. but I
didn't
find further document to explain the concept. RHEL 8.2 also
support
"disaster recovery cluster". so I think maybe a single node
disaster
recovery cluster is not bad.
I think corosync is still necessary under single node
cluster. or
is there other new style of configuration?
thanks for help!
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--
Regards,
Reid Wahl, RHCA
Senior Software Maintenance Engineer, Red Hat
CEE - Platform Support Delivery - ClusterHA
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