Re: Swap size recommendations

[Bryan Vyhmeister <netbsd%bsdjournal.net@localhost>]

On Mon, Jun 14, 2010 at 8:57 AM, Greg Troxel <gdt%ir.bbn.com@localhost> wrote:
> Swap size recommendations have been historically difficult.  The real
> issue is that the person making the recommendation can't know what you
> are going to do with the system.
>
> Enduring points from the arguments:
>
>  swap should be bigger than RAM, so you can have crashdumps
>
>  RAM + swap should be big enough for the total virtual size of all the
>  program s you want to run at once
>
>  if programs are paging all the time, you should get more RAM somehow
>
> Given all that, "make swap a little bigger than RAM" ends up being
> pretty reasonable, because if that's not enough swap you really want
> more RAM.

In my two Mac mini's I have 4GB of swap space with the machines maxed
out with 3GB of memory. With the 320GB hard disks I have in them it is
no big deal. I never use swap but just in case it's there. It's much
better to allocate it now with some headroom than to run into memory
issues without it. My first install was with no swap space and 256MB
for dom0. I started hitting swap and decided that was a bad idea. Now
I am running with 512MB for dom0 and 4GB of swap. No problems have
come up at all. I am running 8-10 VMs that are a mix of OpenBSD,
CentOS, and FreeBSD HVM domU's and NetBSD PV domU's.

I realize that I can easily change the amount of memory for dom0 with
a reboot but I like the buffer of having plenty of swap just in case.

Bryan