Hi there,
I'm noticing that 'free' shows no swap space in a VE.

I had a good dig through the wiki and man pages and I can't find any 
references to being able to configure a VE to have swap (of its own).

Is this something thats abstracted away (ie the VE gets to use the hosts 
swap as needed) or is there a way to configure swap availability for 
each VE?

Thanks!

On Wed, Aug 22, 2007 at 11:18:53AM +1200, Steve Wray wrote:
 > Hi there,
 > I'm noticing that 'free' shows no swap space in a VE.
 
 > Is this something thats abstracted away (ie the VE gets to use the hosts 
 > swap as needed) or is there a way to configure swap availability for 
 > each VE?


kernel 2.6.18-ovz028stab039.1-smp:  no swap, RAM = PRIVVMPAGES*256

kernel 2.6.18-8.el5.028stab031.1:  swap = host swap, RAM = host RAM
This does not seem right.

I haven't done much with the el5 kernel yet, my server is still using
2.6.18-ovz028stab039.1-smp.


-- 

   E Frank Ball                efball@efball.com

Steve Wray wrote:
> Hi there,
> I'm noticing that 'free' shows no swap space in a VE.
> 
> I had a good dig through the wiki and man pages and I can't find any 
> references to being able to configure a VE to have swap (of its own).

That's correct. You can't control VE swap space directly.
Kernel decides itself what should be preempted to swap in the system
and which data is most rarely used.
This is more efficient from overall performance point of view then having
a separate swap space assigned to each VE and used when VE goes higher some limit.

> Is this something thats abstracted away (ie the VE gets to use the hosts 
> swap as needed) or is there a way to configure swap availability for 
> each VE?

"the VE gets to use the hosts swap as needed"

You get it right. In future versions we likely will have real RAM and SWAP limits
and VE will behave like a real std server, but as I said I still wouldn't recommend
to configure it like that cause disk I/O bandwidth which is used for swapping
is a scare resource and it's not worth swapping out something when there is global
RAM available still.

Thanks,
Kirill

E Frank Ball III wrote:
> On Wed, Aug 22, 2007 at 11:18:53AM +1200, Steve Wray wrote:
>  > Hi there,
>  > I'm noticing that 'free' shows no swap space in a VE.
>  
>  > Is this something thats abstracted away (ie the VE gets to use the hosts 
>  > swap as needed) or is there a way to configure swap availability for 
>  > each VE?
>
>
> kernel 2.6.18-ovz028stab039.1-smp:  no swap, RAM = PRIVVMPAGES*256
>
> kernel 2.6.18-8.el5.028stab031.1:  swap = host swap, RAM = host RAM
> This does not seem right.
>   
This is not the kernel, this is just meminfo virtualization plus newer
vzctl which has --meminfo privvmages:1 by default.
> I haven't done much with the el5 kernel yet, my server is still using
> 2.6.18-ovz028stab039.1-smp.
>
>
>