From: Green, Simon (SGreen@KRAFTEUROPE.COM)
Date: Tue Jul 30 2002 - 10:45:22 EDT
The "sysdumpdev -e" command gives you an estimate of the size of a dump. I
have found that this estimate tends to increase over time; presumably as
more stuff gets loaded into memory. So wait until your system has been
running for a week or so, and be a bit generous with your allocation. If
possible, be VERY generous with the allocation, as if it's wrong you may end
up with an incomplete dump. Allocating a dump device equal in size to real
memory assures you of getting a complete dump, but that could be a bit
excessive these days, with systems having many GB of memory. On the other
hand, disks are bigger and cheaper.
I like to use /dev/hd7, which used to be the dump device in old versions of
AIX; it's not likely to be used for anything else and it's easy to
remember/recognise. However, it doesn't really matter what you call it.
A compromise might be to use a paging space other than hd6, but set it not
to activate at boot. That way you're not "wasting" space and if a dump has
been taken to it it doesn't get overwritten, but you have to remember to
activate it manually after a reboot.
Simon Green
Philip Morris ITSC Europe
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 seldom be appreciated.
> -----Original Message-----
> From: Drew [mailto:apt@DCS-SUCCESS.COM]
> Sent: 30 July 2002 15:29
> To: aix-l@Princeton.EDU
> Subject: Re: Mirroring rootvg with the mirrorvg command
>
>
> Nice. From now on I will mirror the paging space and create a
> separate place
> for my default dump device. Any suggestions on the optimum
> parameters for a
> default dump device?
>
> Drew
>
> (Man this discussion group is great!)
>
> -----Original Message-----
> From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU]On Behalf Of
> Green, Simon
> Sent: Tuesday, July 30, 2002 5:07 AM
> To: aix-l@Princeton.EDU
> Subject: Re: Mirroring rootvg with the mirrorvg command
>
> I usually have a separate dump device, so it can survive a
> reboot and I
> don't have to mess around saving a dump to tape. One could
> get away with
> not mirroring that.
>
> But if you lose a disk with an unmirrored paging space on it
> your system
> will crash. Maybe not immediately, but it _will_ happen.
> Since that's what
> you're tying to avoid by mirroring rootvg it makes no sense
> to exclude any
> paging space.
>
> It's also worth mentioning that if you feel the need to
> mirror rootvg, then
> you really ought to mirror any paging spaces in external
> volume groups, even
> if you feel you don't need to mirror the application data.
>
> Simon Green
> Philip Morris ITSC Europe
>
> 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 seldom be appreciated.
>
> > -----Original Message-----
> > From: Drew [mailto:apt@dcs-success.com]
> > Sent: 29 July 2002 20:39
> > To: aix-l@Princeton.EDU
> > Subject: Re: Mirroring rootvg with the mirrorvg command
> >
> >
> > I thought it was better not to mirror the default dump device
> > which resides
> > (by default) in hd6. At least as far as AIX 4.3.3 is
> concerned. If the
> > default dump device is not on hd6, then it shouldn't matter.
> > I personally do
> > not mirror the paging space because there is no reason to
> > have another disk
> > spinning for a mirrored paging space. Why mirror it when you
> > are just taking
> > up extra resources and adding wear and tear to a disk?
>
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