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:
# xm info
host : lakxen04
release : 2.6.16.60-0.33-xen
version : #1 SMP Fri Oct 31 14:24:07 UTC 2008
machine : x86_64
nr_cpus : 8
nr_nodes : 1
cores_per_socket : 4
threads_per_core : 1
cpu_mhz : 2500
hw_caps :
bfebfbff:20000800:00000000:00000140:000ce3bd:00000000:00000001
total_memory : 32765
free_memory : 9169
max_free_memory : 10705
max_para_memory : 10701
max_hvm_memory : 10667
node_to_cpu : node0:0-7
node_to_memory : node0:9169
xen_major : 3
xen_minor : 2
xen_extra : .0_16718_18-0.3
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler : credit
xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : 16718
cc_compiler : gcc version 4.1.2 20070115 (SUSE Linux)
cc_compile_by : abuild
cc_compile_domain : suse.de
cc_compile_date : Thu Oct 9 15:34:16 UTC 2008
xend_config_format : 4
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?
Thanks,
James
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On Tue, Oct 6, 2009 at 15:10, James Pifer <jep@obrien-pifer.com> 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 -- Stephen Leacock - "I detest life-insurance agents: they always argue that I shall some day die, which is not so." - http://www.brainyquote.com/quotes/authors/s/stephen_leacock.html _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, 2009-10-06 at 15:21 -0400, J wrote:> On Tue, Oct 6, 2009 at 15:10, James Pifer <jep@obrien-pifer.com> 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. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Anyone know if this specific issue has been addressed? Trying not to reboot your domU''s very often is admirable, but sometimes, especially Windows domU''s you have to reboot. I''m on a little bit older version of xen, 3.2.x, but would be nice to know if the newer versions address this specific issue. As I said, one of my servers has 10 gb of ram free, but says it''s unable to allocate memory when restarting an existing domU or trying to bring up a new domU. Thanks, James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users