From: pSeries AIX Geek (aixgeek@YAHOO.COM)
Date: Tue Apr 15 2003 - 15:35:43 EDT
I'm back again with the big VG issue. My client wants
to pursue them.
The "drawbacks" with big VGs, as I see them are:
1. Slow VGDA updates.
2. Past AIX defects
3. Can't go back to AIX 4.3.0 or before.
I don't consider #3 a problem, frankly.
Can anyone point to any specific examples of how slow
VGDA updates will take? If it's just a slowness
issue, I think I can live with that (we'd only need to
do VGDA updates only when we increase a file system,
and those are generally planned).
If there's a potential corruption issue, then that's a
different story. The box is currently at AIX 4.3.3 ML
08, but it will probably go to AIX 5.1 or AIX 5.2 by
the end of the summer.
Can anyone relate any practical information about #1
or #2, and can anyone relate any new issues I haven't
considered?
Quite honestly, it would be easiest for the customer
to use big VGs if at all possible, but if it's really
not feasible, then a second VG would be the route we'd
take. This customer's environment is probably the
"textbook" case for why IBM introduced the option.
- pAG
--- "Green, Simon" <Simon.Green@EU.ALTRIA.COM> wrote:
> I would advise against this, unless you have no
> choice.
>
> I set up a BigVG a few years ago and it was a major
> pita!
>
> The big problem was that all LVM commands seemed to
> take forever.
> It's bad enough when you've got time for a cigarette
> between
> issuing lsvg and getting any output; it's worse when
> a VG recovery
> takes two hours instead of 20 minutes. (Trying to
> get it to work
> correctly at our Disaster Recovery tests was a
> nightmare.)
>
> If you have to do it, treat it as a temporary
> solution: try to
> convince management to split the VG later on; it'll
> be much less
> painful in the long run.
>
> Simon Green
> Altria ITSC Europe s.a.r.l.
>
> AIX-L Archive at
> http://marc.theaimsgroup.com/?l=aix-l&r=1&w=2
> AIX FAQ at http://www.faqs.org/faqs/aix-faq/
>
> N.B. Unsolicited email from vendors will not be
> appreciated.
>
> > -----Original Message-----
> > From: pSeries AIX Geek [mailto:aixgeek@YAHOO.COM]
> > Sent: 08 April 2003 16:30
> > To: aix-l@Princeton.EDU
> > Subject: Big VGs
> >
> >
> > I inherited a system that has a volume group with
> > thirty two 8GB Shark LUNs. Obviously, we're maxed
> > out. The current plan is to move to a "big" VG.
> > There's some 150 free PPS on one disk, so I do
> have
> > the option of using lmigratepp to move the first
> {x}
> > partitions from each disk to the free section in
> the
> > VG.
> >
> > [Rebuilding a new VG or using another VG is also
> an
> > option, but for various reasons, the DBAs are
> leaning
> > toward this one.]
> >
> > My questions:
> >
> > 1. AIX 4.3.3 ML 10. Any known problems with big
> VGs?
> > I couldn't see any APARs.
> >
> > 2. Exactly how many free PPs do I need at the
> start
> > of each disk?
> >
> > Other than that, I assume that there aren't any
> issues
> > with just shutting everything down and running
> "chvg
> > -B VGname" (after running a database backup, of
> > course).
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