Xen users - Apr 2008 - Fwd: Dinamically allocated memory in a virtual machine

Hello, i have been looking for some info about how to expand dinamically the
memory of my virtual machines, can someone give me a tip please?

 I have basic skills with the xen world, just now  iam only able to create
virtual machines from a template, manage them a little with xen tools, and i
don''t know how to manage dinamically this settings, memory, disk space
of
the virtual machine etc, when the machines are running.

Is even possible, or can''t be done?

Im using xen over debian etch.

Thanks,

Madrivi.


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Hi Madrivi,
> Hello, i have been looking for some info about how to expand dinamically
> the memory of my virtual machines, can someone give me a tip please?
Sure.
>  I have basic skills with the xen world, just now  iam only able to create
> virtual machines from a template, manage them a little with xen tools, and
> i don''t know how to manage dinamically this settings, memory, disk
space of
> the virtual machine etc, when the machines are running.
>
> Is even possible, or can''t be done?
The "xm mem-set" command can be used to resize the memory a domain is
using.
You can use it to shrink the domain''s memory or to grow it again.

The "xm mem-max" command is used to set the maximum memory a domain is
allowed
to have.

Note that ordinarily XenLinux does not support being grown beyond its initial 
a location of RAM.  If you want to be able to do this, you need to add 
something like mem=4G (for a maximum of 4G) to the domain''s kernel
command
line in order to tell it how big it might get.  This is so the guest Linux 
can size its tables to fit the amount of memory.

The above refers to paravirtualised (PV) domains.  If you install a PV driver 
kit you should be able to resize the memory of a fully virtualised (HVM) 
domain but I don''t think it can grow beyond its initial size.

Cheers,
Mark

-- 
Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/)

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Hi,

Am Donnerstag, 1. Mai 2008 02:57 schrieb Mark Williamson:
[..]
> Note that ordinarily XenLinux does not support being grown beyond its
> initial a location of RAM.  If you want to be able to do this, you need to
> add something like mem=4G (for a maximum of 4G) to the domain''s
kernel
> command line in order to tell it how big it might get.  This is so the
> guest Linux can size its tables to fit the amount of memory.
i''ve tested this with Xen 3.0.3 (Debian 4.0) and it doesn''t
work as expected.
I''ve configured a domU with 256MB RAM and set "mem=4G" as
kernel option. The
domU kernel says something about a lot of high mem available. The started 
domU sees 256MB RAM. All OK. If i mem-set to more than 256MB RAM the domU 
(free or top) doesn''t recognize it. xm list shows the additional RAM,
but
this is also true if i don''t start with mem=4G.

Am I doing something wrong or do I have a too old xen version?

What are the proposed ways to manage RAM with which version of xen?

For now, i''ve to set memory in domU config to a high value and ballon
down the
memory shortly after startup so that i''m able to give more RAM when i
need it
without a reboot.


-- 
greetings

eMHa


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