Very large swap

[Nikos Vassiliadis]

On 10/14/2011 8:08 AM, Dennis Glatting wrote:
>
> This is kind of stupid question but at a minimum I thought it would be
> interesting to know.
>
> What is the limitations in terms of swap devices under RELENG_8 (or 9)?
>
> A single swap dev appears to be limited to 32GB (there are truncation
> messages on boot). I am looking at a possible need of 2-20TB (probably
> more) with as much main memory that is affordable.

The limit is raised to 256GB in HEAD and RELENG_8
http://svnweb.freebsd.org/base?view=revision&revision=225076

> I am working with large data sets and there are various ways of solving
> the problem sets but simply letting the processors swap as they work
> through a given problem is a possible technique.

I would advise against this technique. Possibly, it's easier to design
your program to user smaller amounts of memory and avoid swapping.

After all, designing your program to use big amounts of swapped out
memory *and* perform in a timely manner, can be very challenging.

Nikos