[colug-432] Swap science, was: Install and Manually Partition Debian

[Brian Miller]

On 03/16/2014 05:20 PM, R P Herrold wrote:
>
> Why as to a large swap?  In the former times a swap 2X
> physical ram 'ruled the roost'.  More recent lore is 'if
> you are into swap', you are paying a high price for r/w
> speeds onto spining rust
>
>
> Last week, I was asked swap sizing strategy, but did and do
> not know of a CURRENT and evidence based 'general answer' --
> with VM's from the Hypervisor perspective, we KNOW from
> statistics reduction, that our choke point is drive RW, and so
> avoiding swap just makes sense.  VM's would pay that penalty
> as well
>
> Does anyone have some recent 'science' as to swap sizing
> considerations?
>
> -- Russ herrold

This isn't exactly based on research, but my current practice is to 
provide a small swap space on my virtual machines (say, 500 MB), and 
then give the guest enough memory to run the application.  If the server 
writes a small amount to swap, I don't worry about it.  But if swap 
keeps growing, I generally increase the amount of RAM.  Unless it looks 
like it's caused by a memory leak.  Then I tell the application admins 
to set a schedule to re-start their application.  I'll even offer to set 
up a notification email to tell them when swap gets to 75% full, if they 
want.