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 :-) -- rgds Stephen