[ale] On swap space (was Re: who is eating my drive)

[The Don Lachlan]

On 05/31/2011 05:37 PM, Jim Kinney wrote:
> On Tue, May 31, 2011 at 4:05 PM, The Don Lachlan <ale-at-ale.org
> <http://ale-at-ale.org>@unpopularminds.org <http://unpopularminds.org>>
> wrote:
>     I think we're working on different systems. Swap costs pennies a GB, RAM
>     costs many dollars per GB. We should be using swap because it's
>     C-H-E-A-P-E-R.
> I guess it really depends on how the system is going to be used. Most of
> the stuff I run is bordering on or deep into high performance. Swap is
> _bad_ from my view. RAM disks are good. Screw the cost! More speed!
> I used to joke (only half serious) that I want twice as much ram as disk
> space. Boot, copy drive to ram and run.

There is a place for that. Plenty of systems can run happily out of RAM, 
but that's not what we're talking about. I mean, if you want to argue 
for removing disk, that's an entirely different conversation.

I said:
>     Regular paging between physical RAM and swap space can be expensive to a
>     system's performance; I would say that we shouldn't be paging in/out
>     often, if at all, but paging out is A Good Thing <tm>.

In a perfect world there'd be infinite space and no latency. In this 
world, there's finite space and infinite latency. And budgets. Paging 
moves infrequently accessed data from RAM (low latency, small space, 
expensive) to swap (higher latency, huge space, dirt cheap). Paging 
in/out a lot is bad, paging out is A Good Thing <tm>.

-L