We are planing on moving to xl but have not done so yet. Our xend configs are untouched so they should match what they were when the xen-* packages were installed. We force dom0 to 1024MB of memory via grub. On a couple servers were we've seen this issue we've had 16+ GB of memory free and the domU was requesting something small like 2GB. -- Shaun ------ Original Message ------ From: "George Dunlap" <dunlapg at umich.edu> To: "Shaun Reitan" <shaun.reitan at ndchost.com>; "Discussion about the virtualization on CentOS" <centos-virt at centos.org> Sent: 6/24/2016 4:28:53 AM Subject: Re: [CentOS-virt] Cannot allocate Memory >On Wed, Jun 22, 2016 at 6:45 PM, Shaun Reitan ><shaun.reitan at ndchost.com> wrote: >> Any of you guys ever seen an issue with Xen 4.4 were xm cannot create >>a >> guest because of what looks like an issue allocating memory even >>though xm >> info shows like 5x the amount of free memory needed? We are still >> unfortunately still using xm... it's on my list, i know.. >> >> We've had this happen on a couple hosts now. Only way to resolve >>seams to >> be rebooting the host. I'm going to update the host to latest Xen >>4.4 now >> hoping this is a old bug. > >xend hasn't had much love in years, so it's fairly unlikely that this >has been fixed. > >> Here's from xen logs >> >> [2016-06-22 09:13:50 1958] DEBUG (XendDomainInfo:105) >> XendDomainInfo.create(['vm', ['name', 'xxx'], ['memory', 2048], >> ['on_xend_start', 'ignore'], ['on_xend_stop', 'ignore'], ['vcpus', >>2], >> ['oos', 1], ['image', ['linux', ['kernel', >>'/kernels/vmlinux-2.6.18.8-4'], >> ['videoram', 4], ['args', 'root=/dev/xvda ro xencons=tty console=tty1 >>'], >> ['tsc_mode', 0], ['nomigrate', 0]]], ['s3_integrity', 1], ['device', >>['vbd', >> ['uname', 'phy:vg/fs_6818'], ['dev', 'xvda'], ['mode', 'w']]], >>['device', >> ['vbd', ['uname', 'phy:vg/fs_6819'], ['dev', 'xvdb'], ['mode', >>'w']]], >> ['device', ['vif', ['rate', '40mb/s'], ['mac', >>'FE:FD:48:01:F1:E7']]]]) >> [2016-06-22 09:13:50 1958] DEBUG (XendDomainInfo:2504) >> XendDomainInfo.constructDomain >> [2016-06-22 09:13:50 1958] DEBUG (balloon:187) Balloon: 7602632 KiB >>free; >> need 16384; done. >> [2016-06-22 09:13:50 1958] ERROR (XendDomainInfo:2566) (12, 'Cannot >>allocate >> memory') >> Traceback (most recent call last): >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 2561, in _constructDomain >> target = self.info.target()) >> Error: (12, 'Cannot allocate memory') >> [2016-06-22 09:13:50 1958] ERROR (XendDomainInfo:490) VM start failed >> Traceback (most recent call last): >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 475, in start >> XendTask.log_progress(0, 30, self._constructDomain) >> File "/usr/lib64/python2.6/site-packages/xen/xend/XendTask.py", >>line 209, >> in log_progress >> retval = func(*args, **kwds) >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 2572, in _constructDomain >> raise VmError(failmsg) >> VmError: Creating domain failed: name=xxx >> [2016-06-22 09:13:50 1958] ERROR (XendDomainInfo:110) Domain >>construction >> failed >> Traceback (most recent call last): >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 108, in create >> vm.start() >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 475, in start >> XendTask.log_progress(0, 30, self._constructDomain) >> File "/usr/lib64/python2.6/site-packages/xen/xend/XendTask.py", >>line 209, >> in log_progress >> retval = func(*args, **kwds) >> File >>"/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line >> 2572, in _constructDomain >> raise VmError(failmsg) >> VmError: Creating domain failed: name=xxx > >If you haven't decided to switch to xl, would you mind reposting this >question to xen-users? If you do, please also include the output of >"xl info" after the failure. > >The logs tell us that xend is asking dom0 to free up some memory to >use to create the guest. My guess is that there's a slight mismatch >between how much memory xend things needs to be freed and how much >memory actually needs freeing. > >Thanks, > -George