This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-users] More memory problems.

On Tue, 2009-10-06 at 15:21 -0400, J wrote:
> On Tue, Oct 6, 2009 at 15:10, James Pifer <jep@xxxxxxxxxxxxxxxx> wrote:
> > I have several xen servers running on SLES10SP2. I occasionally have
> > problems with allocating memory. When this happens the only fix I know
> > of is to shut down all the domUs and restart the server. Or at least
> > xend, which affects many of my domUs.
> >
> > I have this problem on two servers right now. One of them has plenty of
> > free memory available. See below:
> > When I try to start a domU I get:
> > # xm start lakvre05
> > Error: [Errno 12] Cannot allocate memory
> > Usage: xm start <DomainName>
> >
> > Start a Xend managed domain
> >  -p, --paused                   Do not unpause domain after starting
> > it
> >  -c, --console_autoconnect      Connect to the console after the
> > domain
> >                                 is created
> >
> > Any suggestions for working around this or is restarting xend the only
> > option?
> add dom0_mem=XXXM to the Xen entry (on the first line for this boot
> option) in menu.lst.
> Make XXX something rational for Dom0... I usually set dom0 on my
> systems to 512M or 1024M depending on how much physical ram the system
>  has.
> That usually fixed the problem for me.  The problem is or was (not
> sure if it was ever actually fixed) in the code that handles
> ballooning the memory.  After a while, Xen will just stop shrinking
> Dom0's memory allocation, OR, it's a race and the freeing of memory
> from Dom0 happens slower than the allocating of memory for the new
> DomU.
> Then it gets stuck and the only fix, as you've mentioned, is to reboot.
> So limiting Dom0's memory allocation to something small leaves the
> rest of the system memory unallocated and unused and thus free for
> handing out to DomUs.
> This can also happen if you have a lot of DomUs being installed and
> deleted, or stopped and started frequently.
> Cheers
> Jeff

Unfortunately I already have that set to 2048. Because of previously
issues with this exact problem, I have not had a lot of
starts/stops/reboots/deletes. I don't know what constitutes as "a lot"
though. There are 12 domUs on the server. dom0 has been up for 107 days.
The highest id number for a domU is currently 43. Honestly I'm not sure
how it's even that high.


Xen-users mailing list

<Prev in Thread] Current Thread [Next in Thread>