[xenpreview-dev] boot ine dom0_mem=memory

[Lynn Bendixsen]

With apologies, I beg to differ in some respects.  I have not used the dom0_mem parameter nor have I had to reduce dom0 memory to be able to install a vm for at least 2 months now.  Perhaps that is because I am using SLES10 SP1 and bug fixes have gone in for that to fix the old memory problems mentioned here.  I see as a more serious problem the fact that the minimum memory that Dom0 will balloon down to is 196MB and it sounds like many users are running a GUI in Dom0 and with that 196 MB just isn't enough (I suggest 512MB minimum).  The "maximum" memory available for a VM in the vm-install tool uses the 196MB number for its calculations.

I recommend manually changing the minimum memory amount if you run default (GUI in Dom0) by changing the (dom0-min-mem 196) line in the /etc/xen/xend-config.sxp file to be (dom0-min-mem 512).  This should guarantee that Dom0 does not auto-balloon down below 512MB.  (The 196MB number is fine if you run headless :)

my 2c worth,
Lynn

>>> On Wed, May 9, 2007 at 12:09 PM, in message
<C65897B92B0CDB4DA82310A2C988309D586BED at GTLBMLEXS0016.bagmail.net>,
<Jan.Albrecht at bertelsmann.de> wrote: 
> dom0 does run in SLES10 and the only "big" application is the zmd. As
> this does run fine with KDE on my 512MB workstation I assume 512 would
> be fine.
> 
> Thanks for your help all!
> 
> Jan 
> 
>> ----- Original Message-----
>> From: Manzer, Kirk [mailto:kirk.manzer at hp.com] 
>> Sent: Wednesday, May 09, 2007 8:00 PM
>> To: Albrecht, Jan, NMI- DC
>> Cc: xenpreview- dev at forge.novell.com
>> Subject: RE: [xenpreview- dev] boot ine dom0_mem=memory
>> 
>> Normally I specify 1 GB, most of my servers have more than 12 GB of
>> memory.  It is overkill at 1 GB but would rather fall on the side of
>> safe.  This is a base dom0 doing nothing but running XEN and 
>> domUs.  If
>> dom0 is also doing other tasks I allocate addition memory to ensure no
>> memory contention.  You could run with 512mb for dom0, but you would
>> have to be confident in what dom0 is doing, and that things like
>> automatic updates to the OS do not cause problems.
>> 
>> 
>> Kirk A. Manzer 
>> HP
>> TSG Solution Alliances, Linux
>> Phone: (281)- 514- 4979 
>> Cell: (832)- 563- 8120 
>> Fax: (281)- 514- 5802 
>> kirk.manzer at hp.com 
>> 
>> 
>> ----- Original Message-----
>> From: Jan.Albrecht at bertelsmann.de 
>> [mailto:Jan.Albrecht at bertelsmann.de] 
>> Sent: Wednesday, May 09, 2007 12:52 PM
>> To: Manzer, Kirk
>> Cc: xenpreview- dev at forge.novell.com
>> Subject: RE: [xenpreview- dev] boot ine dom0_mem=memory
>> 
>> Hi, 
>> 
>> > ----- Original Message-----
>> > From: Manzer, Kirk [mailto:kirk.manzer at hp.com] 
>> > Sent: Wednesday, May 09, 2007 7:34 PM
>> > 
>> > I have been using the dom0_mem parameter on the kernel for 
>> a while. I
>> > limit dom0 to either 1 or 2 GB of memory depending on what 
>> > the server is
>> > doing, then I have no issues starting and domUs.  Prior to using
>> > dom0_mem I was constantly having issues with starting domUs.
>> 
>> Can you specify "depending on what the server is doing"?
>> I'm running databases in 2 of the domains, one is just testing and one
>> for development (compiling etc.)
>> When does your dom0 need 1GB and on the other hand 2GB? I 
>> would suggest
>> the dom0 should always use as less memory as possible?
>> 
>> Jan
>> 
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