From: James Jackson (James.Jackson@MAIL.STATE.AR.US)
Date: Tue Oct 29 2002 - 09:46:11 EST
Simon,
Thanks for your thorough response. Your deductions regarding the cause of
the problem appear to be right on the money.
I'm guessing the only way to import the VG on the Dev. node is to vary it
off on the Prod. node, correct? Would it be absolutely necessary to stop
the cluster to do this? I've already exported the VG on the Dev. node, and
I'm stuck right now, since I apparently can't import it while it's active on
the Prod. node; mark it off to my lack of HACMP experience.
I'm doing all of this to prepare for a takeover test in advance of adding
some ESS SAN storage. I want to make sure everything is stable before I
start mucking with maintenance levels and device drivers.
I've found the HACMP manuals to be pretty useful, as well, though I wish
they went a bit deeper on troubleshooting.
As always, thanks for your well-reasoned responses to this list. I'll look
into the Yahoo! HACMP group.
Regards,
James Jackson
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Subject: RE: HACMP, hdisk with no VG assignment.
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From: "Green, Simon" <SGreen@KRAFTEUROPE.COM>
Subject: Re: HACMP, hdisk with no VG assignment.
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At some point in the past, someone has added another disk to the volume
group on the Production node. The volume group definitions now need to be
synchronised on each node in the cluster.
In all likelihood, in the event of a takeover "Lazy Update" would work:
HACMP determines that the VGDA has changed and re-imports it on the standby
node.
This adds a little time to the takeover. There are a few situations it
can't handle, though, so it's better to synchronise them when you have a
chance.
The simplest way is to stop your cluster, vary off the VG on your Production
node then import it on the Development node, using importvg -L VGName HDisk
where HDisk is one of the disks in the VG, (not the new one).
If you're feeling particularly paranoid - sorry; cautious - you could do an
exportvg on your Development node, then a normal importvg. If you do this,
be sure to specify the VG Major Number, (-V option).
It's worth checking the volume group at each end to make sure that they're
not set to vary on automatically at startup. I know a normal importvg sets
this
on; I'm not sure about importvg -L.
If it's mirrored, check the quorum, too.
Since you've just picked this up, it might be worth checking a few other
things. Make sure that the VG Major Number for each VG is the same on both
nodes, (ls -l /dev/VGName). No reason to think that they won't be, but
someone's been a bit sloppy about keeping them synchronised in the past, so
it won't hurt to check.
Also, do a full verify of the cluster. Easiest to do this through smit.
smitty hacmp; Cluster Configuration; Cluster Verification; Verify Cluster
Hopefully you have some documentation. If so, you ought to check that it's
accurate: network adapters defined as described etc. If it doesn't exist
you could make some now.
I'd quite like to do a takeover as well, to check that it works correctly
and make sure that I'd seen one from start to finish; it's good to see a
controlled takeover, so that if it happens for real you'll be able to
recognise anything out of the ordinary.
There are some HACMP Redbooks, but to be honest I haven't found them to be
very useful. Still; might be worth a look. The normal HACMP manuals are
quite good. The Configuration and Administration guide(s) are the most
useful.
If you start having to do much with this, there's a Yahoo! HACMP group which
you might find interesting. Not very active, but some useful expertise.
Simon Green
Philip Morris ITSC Europe
AIX-L Archive at http://marc.theaimsgroup.com/?l=aix-l&r=1&w=2
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-----Original Message-----
>From: James Jackson [mailto:James.Jackson@MAIL.STATE.AR.US]
>Sent: 28 October 2002 22:44
> I have inherited a two-node HACMP cluster with SSA disks. Two of the
volume
> groups on the Production node contain filesystems that are configured to
> failover to the Development node. However, one of the hdisks on the
> Development node does not have a corresponding reference to the volume
group
> on the Production node. Rather than belonging to VG "backvg", the hdisk
has
> a VG reference of "none". The hdisk does, however, reference the correct
> PVID. How should I go about correcting this?
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