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Re: [Xen-users] Swap space for DomU

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Swap space for DomU
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Fri, 4 Jan 2008 17:23:53 +0000
Cc: Matthew Crocker <mcrocker@xxxxxxxxxxx>
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> Should I create a file on Dom0 and assign it for a DomU for use as
> swap space or should I just overcommit my system RAM and have Dom0
> handle all of the swap?

Guests have to do their own swapping, dom0 can't do it for them.  Under Xen 
you have to carve up the physical memory amongst virtual machines - each of 
them gets a "hard" allocation of physical memory.  If you want them to be 
able to overcommit memory then you'll need to configure them each to use 
swap.

The fact that dom0 can't overcommit domU memory and do swapping is a technical 
limitation of Xen, partly imposed by its design.  However, the guests are 
arguably better placed to decide what memory is important to them and what 
memory they want to swap.

> What happens with swap space during a live move if I use a file per
> DomU.  Does the move script copy the swap file over as well?

I'll follow this up in other mails...

Cheers,
Mrak


-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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