[gpfsug-discuss] GPFS Remote Cluster Co-existence with CTDB/NFS Re-exporting

[Howard, Stewart Jameson]

Hi Hajo,


Specifically regarding this point...


"""

If remote clusters are even out of the management ability/responsiblity of the cluster admin, remote firewalls/network settings  can have seriously impact on the local cluster without the ability to fix the problem.

"""


...I was advised by IBM support (after the dust settled) that there is the `mmexpelnode` command, which will forcibly expel a node from the cluster.  This command accepts an option that will not allow the offending node to mount any disks or rejoin the cluster until it is cleared from an "expelled nodes" list.


The caveat here, mentioned in `man mmexpelnode`, is that moving the cluster manager node, either administratively or by failure, will cause the list of expelled nodes to get cleared, which in turn allows the offenders to rejoin, even if they haven't been fixed yet.


Hope that helps,


Stewart

________________________________
From: gpfsug-discuss-bounces at spectrumscale.org <gpfsug-discuss-bounces at spectrumscale.org> on behalf of service at metamodul.com <service at metamodul.com>
Sent: Wednesday, December 16, 2015 8:39 AM
To: gpfsug main discussion list
Subject: Re: [gpfsug-discuss] GPFS Remote Cluster Co-existence with CTDB/NFS Re-exporting

...
last week, you are in for one wild ride.  I would also point out that the flapping did not stop until we resolved connectivity for *all* of the clients, so remember that even having one single half-connected client is poisonous to your stability.
...
In this context i think GPFS should provide somekind of monitoring better than ping. In the good old days remote clusters even over wan might not exist that often but i think it changed pretty much nowadays..

If remote clusters are even out of the management ability/responsiblity of the cluster admin, remote firewalls/network settings  can have seriously impact on the local cluster without the ability to fix the problem. Something nobody would like to see.

With kind regards
Hajo

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