RAM question for everyone!

[Gilboa Davara]

On Fri, 2009-01-23 at 15:43 +0000, Dan Track wrote:
> I was recently asked a question about how much RAM should there be
> within a server given that the APP uses 8GB of Memory, should I buy
> 10Gig of memory and have a small harddrive and no swap space? Would
> this configuration allow everything in my OS to run from RAM and not
> from swap? If this is the case then there's no need to ever create
> swap, is there?!?
> 
> Your thoughts are appreciated.
> 
> Thanks
> Dan
> 

Of the top of my head:

Memory:
If the machine is designed to run a single application and -nothing-
else, 9-10GB will do. However, if you plan to have, say local and remote
X, VNC, I'd add ~2GB the mix.

Swap:
Always setup some kind of swap - at-least 1-2GB. Disk space is cheap,
but if you somehow miscalculate the amount of memory your application
needs - even by 5% - the lack of available memory will trigger the OOM
killer. (Which tends to produce problematic results... such as killing
sshd and getties [happened to me once...])

In general, I usually setup 2-4GB swap on desktops, and 8GB of
workstations/servers.

E.g. I'm typing this on a dual Xeon workstation with 8GB of memory and
8GB of swap and less than 71M of swap is being used.

- Gilboa