[afnog] Xen can only see 2.9G of 8G RAM on Dell R200 with CentOS 5.5

[Hugo Lombard]

On Fri, Apr 29, 2011 at 01:28:38PM +0200, Shepherd Magumo wrote:
>    Thanks Hugo, It's all starting to make sense, there 4 active DomU's.
>    I recently put up a SNMP used memory monitor on Dom0 after experiencing
>    performance issues. The monitor would hit roughly around 2.9GB and the
>    guests start slowing down in performance. So I assumed that was the total
>    mem.

Does this SNMP used memory monitor see the total amount of memory in
Dom0 decrease each time you start up a new DomU?

>    Forgive me there, I am a xen newbie. So how would I best measure and graph
>    DomU's memory preferably from Dom0 without installing SNMP clients on the
>    guests?
> 

Are you interested in how much memory in the DomU is used and how much
free, or just how much memory is allocated to the DomU?  The former
won't be possible from Xen/Dom0 directly, as it doesn't know/care about
that level of detail (although I'd love to be proved wrong on that).
The latter depends on how you are gathering the stats.  libvirt can
expose that (and more) or you can try a hack like

 http://pookey.co.uk/wordpress/archives/55-monitoring-xen-via-snmp-update

to expose it via SNMP.

-- 
Hugo Lombard