[gpfsug-discuss] A cautionary tale of upgrades
Mathias Dietz
MDIETZ at de.ibm.com
Fri Jan 11 14:58:20 GMT 2019
Hi Simon,
you likely run into the following issue:
APAR IV93896 - https://www-01.ibm.com/support/docview.wss?uid=isg1IV93896
This problem happens only if you use different host domains within a
cluster and will mostly impact CES. It is unrelated to upgrade or mixed
version clusters.
Its has been fixed with 5.0.2, therefore I recommend to upgrade soon.
Mit freundlichen Grüßen / Kind regards
Mathias Dietz
Spectrum Scale Development - Release Lead Architect (4.2.x)
Spectrum Scale RAS Architect
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From: Simon Thompson <S.J.Thompson at bham.ac.uk>
To: "gpfsug-discuss at spectrumscale.org"
<gpfsug-discuss at spectrumscale.org>
Date: 11/01/2019 15:19
Subject: [gpfsug-discuss] A cautionary tale of upgrades
Sent by: gpfsug-discuss-bounces at spectrumscale.org
I?ll start by saying this is our experience, maybe we did something stupid
along the way, but just in case others see similar issues ?
We have a cluster which contains protocol nodes, these were all happily
running GPFS 5.0.1-2 code. But the cluster was a only 4 nodes + 1 quorum
node ? manager and quorum functions were handled by the 4 protocol nodes.
Then one day we needed to reboot a protocol node. We did so and its disk
controller appeared to have failed. Oh well, we thought we?ll fix that
another day, we still have three other quorum nodes.
As they are all getting a little long in the tooth and were starting to
struggle, we thought, well we have DME, lets add some new nodes for quorum
and token functions. Being shiny and new they were all installed with GPFS
5.0.2-1 code.
All was well.
The some-time later, we needed to restart another of the CES nodes, when
we started GPFS on the node, it was causing havock in our cluster ? CES
IPs were constantly being assigned, then removed from the remaining nodes
in the cluster. Crap we thought and disabled the node in the cluster. This
made things stabilise and as we?d been having other GPFS issues, we didn?t
want service to be interrupted whilst we dug into this. Besides, it was
nearly Christmas and we had conferences and other work to content with.
More time passes and we?re about to cut over all our backend storage to
some shiny new DSS-G kit, so we plan a whole system maintenance window. We
finish all our data sync?s and then try to start our protocol nodes to
test them. No dice ? we can?t get any of the nodes to bring up IPs, the
logs look like they start the assignment process, but then gave up.
A lot of digging in the mm korn shell scripts, and some studious use of
DEBUG=1 when testing, we find that mmcesnetmvaddress is calling ?tsctl
shownodes up?. On our protocol nodes, we find output of the form:
bear-er-dtn01.bb2.cluster.cluster,rds-aw-ctdb01-data.bb2.cluster.cluster,rds-er-ctdb01-data.bb2.cluster.cluster,bber-irods-ires01-data.bb2.cluster.cluster,bber-irods-icat01-data.bb2.cluster.cluster,bbaw-irods-icat01-data.bb2.cluster.cluster,proto-pg-mgr01.bear.cluster.cluster,proto-pg-pf01.bear.cluster.cluster,proto-pg-dtn01.bear.cluster.cluster,proto-er-mgr01.bear.cluster.cluster,proto-er-pf01.bear.cluster.cluster,proto-aw-mgr01.bear.cluster.cluster,proto-aw-pf01.bear.cluster.cluster
Now our DNS name for these nodes is bb2.cluster ? something is repeating
the DNS name.
So we dig around, resolv.conf, /etc/hosts etc all look good and name
resolution seems fine.
We look around on the manager/quorum nodes and they don?t do this
cluster.cluster thing. We can?t find anything else Linux config wise that
looks bad. In fact the only difference is that our CES nodes are running
5.0.1-2 and the manager nodes 5.0.2-1. Given we?re changing the whole
storage hardware, we didn?t want to change the GPFS/NFS/SMB code on the
CES nodes, (we?ve been bitten before with SMB packages not working
properly in our environment), but we go ahead and do GPFS and NFS
packages.
Suddenly, magically all is working again. CES starts fine and IPs get
assigned OK. And tsctl gives the correct output.
So, my supposition is that there is some incompatibility between 5.0.1-2
and 5.0.2-1 when running CES and the cluster manager is running on
5.0.2-1. As I said before, I don?t have hard evidence we did something
stupid, but it certainly is fishy. We?re guessing this same ?feature? was
the cause of the CES issues we saw when we rebooted a CES node and the IPs
kept deassigning? It looks like all was well as we added the manager nodes
after CES was started, but when a CES node restarted, things broke.
We got everything working again in house so didn?t raise a PMR, but if you
find yourself in this upgrade path, beware!
Simon
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