[nylug-talk] if I have 64GB of RAM, how much swap do I really need?

[Brandorr]

On 31 Aug 2007 11:02:00 -0400, Raj Goel <raj at brainlink.com> wrote:
>
>    If running Linux, 0 swap.
>
>    If Solaris, 64gb.
>    Remember, Solaris does proactive swap-allocation.

For Solaris the main reason you would assign any swap at all is to
capture a kernel/system  crashdump. As of Solaris 8 these dumps get
compressed as they are written to the swap partition. I would suspect,
but would need to verify that an 8GB swap would be sufficient to hold
a compressed RAM image from a 64GB system.

Basically Solaris dumps to the swap slice, and upon bootup moves the
dump to a special path on the root filesystem. "/var/crash/hostname"

Cheers,
Brian

> -- Raj
>
> Rajesh Goel, CISSP
> cell (917) 685-7731
> CTO: Brainlink International, Inc.
> "IT Crisis Management and Solutions"
> -----Original Message-----
> From: Heow Eide-Goodman <lists at alphageeksinc.com>
> Date: Friday, Aug 31, 2007 10:54 am
> Subject: Re: [nylug-talk] if I have 64GB of RAM,        how much swap do I really       need?
> To: NYLUG Technical Discussion <nylug-talk at nylug.org>Reply-To: NYLUG Technical Discussion <nylug-talk at nylug.org>
>
> On Fri, 2007-08-31 at 10:45 -0400, H. G. wrote:
> >
> >> With 64 GBs of memory, do you even need swap....?
> > The real question is what kind of usage are you anticipating?
> >
> >That's sort of what I was expecting.  :-)  It's running at between 50 to
> >70% capacity, with multiple developers (read: multiple memory-DBs)
> >
> >Actually, I think the real question is if the DB can simply stop
> >grabbing RAM and fail before taking the rest of the system down with it.
> >
> >- h
> >
> >
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-- 
- Brian Gupta

http://opensolaris.org/os/project/nycosug/