On Wed, Oct 29, 2008 at 07:07:03PM -0700, John R Pierce wrote:
Stephen Harris wrote:
In older BSD systems (eg around SunOS 4 times or before) swap space was utilised oddly; all memory was allocated from swap, so you needed _at least_ <physmem> of swap just to use all your real memory! So if you added <physmem> of swap then your total virtual memory size was still only <physmem>. No help! So the rule of thumb came along that said "swap = 2*<physmem>" and that gave you a VM of 2*<physmem>.
now, on late model Solaris, 'swap' is also used as tmpfs, which /tmp and
You also had this option on SunOS4 but it wasn't used by default and had a lot of limitations and didn't really work too well for /tmp (IIRC, didn't support FIFOs and some other file types). The Solaris version (first appeared in Solaris 2.1, so it's not _new_) is a LOT better :-)
/var/run utilizes by default, so you definitely want to allocate sufficient swap space for this at least, regardless of how large your physical memory is.
And, no matter what, ensure you limit your /tmp size with the size=####m option in vfstab, otherwise someone will clobber your machine!
To bring this back to Linux... Linux _also_ does have tmpfs which works similarly to Solaris. If you use that then also remember the size option :-)