On 8/21/07, Richard W.M. Jones <rjones@xxxxxxxxxx> wrote:
Justin Conover wrote:
[These are a couple of frequently asked questions ... do we have an FAQ?]
> How can you free up memory when you shut a guest down? Give back to
> Domain-0 so you can start another one up?
Domain-0 doesn't recover the memory when a domain shuts down. The
assumption (within Xen) is that another domain will be starting up
shortly, so there is no point wasting time returning the memory to Domain-0.
However the memory hasn't just gone away, as your question implies. The
hypervisor is still managing that free memory, and will give it to the
next guest which starts up.
If you really want to give the free memory back to Domain-0, then I
think you can do it by:
virsh setmem Domain-0 <kb>
where <kb> is the total number of kilobytes that you want Domain-0 to
have (ie. current size + size of freed guest -- you have to calculate
this for yourself).
> Also, were are the profiles for xen stored? For example I create all of
> them under /vm/xen/blah if I decide to delete blah1 and create a new one
> named blah1 it says it is already there, even though I removed it.
Since Xen 3.0.3 or 3.0.4, I forget exactly which, Xen manages the
profiles in its own private place. So there are no configuration files.
I agree that this is very annoying, but that's the way Xen forces us
to do it.
To view or edit a configuration file, you now have to do:
virsh dumpxml domain > domain.xml
edit domain.xml
virsh define domain.xml
('virsh define' only works if the domain has been shutdown, so if it is
still running then shut it down first using 'virsh shutdown').
If you want to make a change to a running domain, there are some changes
which you are allowed to do, basically adding and removing block and
network devices, and adding and removing memory. The commands to use are:
virsh attach-device
virsh attach-disk
virsh attach-interface
virsh detach-device
virsh detach-disk
virsh detach-interface
virsh setmem
virsh setmaxmem
(Just do 'virsh help command' to get help on each of those commands).
Rich.
--
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Very nice, thank you.
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