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xen-users
RE: [Xen-users] I need some answers please
Yes, the point of a pool is to be able to
move a VM between physical nodes.
You cannot span one VM across multiple
physical nodes. That is not how virtualization works. For example,
if you own two 8GB XCP hosts, you cannot create one big 16GB VM. It
simply does not work that way. What you could do is create VMs that were
smaller than the RAM size of the physical nodes. For example, you could create several
1GB VM and then move them between the XCP hosts as needed.
-----Original Message-----
From:
xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of inas mohamed
Sent: Tuesday, March 08, 2011 4:35
AM
To: xen-users@xxxxxxxxxxxxxxxxxxx;
Simon Hobson
Subject: Re: [Xen-users] I need
some answers please
|
thanks for your reply.
Can I understand from your answer that the resource
pool benefit is for moving VM from one XCP host to another . And not sharing
their resources so I can create VM with RAM size equal to the summation of
two XCP hosts RAM size???
Thanks
--- On Tue, 3/8/11, Simon Hobson <linux@xxxxxxxxxxxxxxxx>
wrote:
From: Simon Hobson <linux@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] I need some answers please
To: xen-users@xxxxxxxxxxxxxxxxxxx
Date: Tuesday, March 8, 2011, 12:13 PM
inas mohamed wrote:
> 1. But if this is the case what is the benefit of using a resource
pool??
Not sure what the question is here. You have a real machine with X amount of
memory. By the time you've allowed some for Xen and Dom0, you have Y left
over. You can snow start guests that use up to Y memory between them. If you
shut one down, you can reuse it's memory for another guest.
If things get unbalanced, you can move a guest to another host that has more
free memory - and given the right setup this can be a live migration.
If you find you need to start another guest, then (depending on the systems)
you may be able to squeeze enough memory by ballooning the other guests down
a bit.
> 2. You said if VM is down it will release the RAM. why when I tried to
find free memory on the host (using free -m) I am not be able to see more
free memory? actually even the total memory is not correct.So, the correct
question is how to find the total and free physical memory on XCP host??
Don't forget that the Dom0 kernel is also running as a (PV) virtual machine.
It will only see the memory given to it by Xen - none of the normal GNU/Linux
tools will show you real memory utilisation for the host machine.
Not sure where else to find the memory utilisation, but it is shown by
xentop.
-- Simon Hobson
Visit http://www.magpiesnestpublishing.co.uk/
for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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