Recommended amount of swap

[RW]

On Mon, 5 Sep 2011 14:48:57 -0500
Dan Nelson wrote:

> In the last episode (Sep 05), Sean Hamilton said:
> > What is the state of the art for the recommended amount of swap in
> > FreeBSD? Both "normal" systems with 512 MB - 8 GB of RAM, and large
> > database systems with around 128 - 256 GB.
> 
> I suggest 2x RAM for systems less than 4gb or so.  Anything more than
> 4GB of swap is probably never going to be used, and if it is used,
> you're just going to thrash your swap device. 

but tmpfs (and swap-backed md devices) can use substantial
amounts of swap without contributing to thrashing. In some cases it
may be possible to justify larger amounts of swap.