> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> boun...@opensolaris.org] On Behalf Of Nico Williams
> As for swap... really, you don't want to swap.  If you're swapping you
> have problems.  

For clarification, the above is true in Solaris and derivatives, but it's not 
universally true for all OSes.  I'll cite linux as the example, because I know 
it.  If you provide swap to a linux kernel, it considers this a degree of 
freedom when choosing to evict data from the cache, versus swapping out idle 
processes (or zombie processes.)  As long as you swap out idle process memory 
that is colder than some cache memory, swap actually improves performance.  But 
of course, if you have any active process starved of ram and consequently 
thrashing swap actively, of course, you're right.  It's bad bad bad to use swap 
that way.

In solaris, I've never seen it swap out idle processes; I've only seen it use 
swap for the bad bad bad situation.  I assume that's all it can do with swap.

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