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1608 discussions

Xen4CentOS issue with running xen domains and a restart
by Johnny Hughes 25 Feb '14

25 Feb '14

There is an error in libvirt when rebooting or shutting down with a running xen domain on Xen4Centos6 When libvirtd tries to shutdown, it tries to suspend the running machine and fails with: VirDomainManagedSave error: this function is not supported by the connection driver Does anyone know how to patch libvirt 0.10.2.x to work around this issue.

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disk io in guests causes soft lockups in guests and host processes
by Dennis Jacobfeuerborn 20 Feb '14

20 Feb '14

Hi, I have a strange phenomenon that I cannot readily explain so I wonder if anyone here can shed a light on this. The host system is a Dell r815 with 64 cores and 256G ram and has centos 6 installed. The five guests are also running centos 6 and are running as a hadoop cluster. The problem is that I see disk-io spikes in the vm's which then cause soft lockups in the guest but I also see hanging processes on the host as if the entire machine locks up for 30-60 seconds. Now I know that having all cluster members running on the same system isn't efficient and that I cannot expect good performance but what I was not expecting is that a guest make host processes hang. Does anyone have an idea what the issue could be here or how I can find out what cause for this behavior is? Regards, Dennis

3 2

Problem with cdrom device on guest
by James B. Byrne 13 Feb '14

13 Feb '14

I have a kvm guest running MS-WinV7 on a CentOS-6.5 host. The WinV7 guest was installed from a CD. It installed correctly and was updated and added to an MS Active Domain without difficulty. I was able to do work on it through the virt-manager console and I was able to shut the system down from the console without problem. I cannot get it to restart however. virsh start brws-ms-v7-37v.brockley.harte-lyne.ca error: Failed to start domain brws-ms-v7-37v.brockley.harte-lyne.ca error: cannot open file '/dev/sr0': No medium found I found this bugzilla report. https://bugzilla.redhat.com/show_bug.cgi?id=709585 Which is curiously marked as CLOSED DEFERRED. The last comment in that bug contains this: > Summary of findings so far: > > format=raw doesn't work with /dev/sr0. Omitting format=raw works. > format=host_device works. > > Apparently, virt-manager specifically asks for "raw". > > Things are different in RHEL-6: format=raw works, > format=host_device doesn't, format=host_cdrom does > (doesn't exist in RHEL-5). Now, in my configuration files there is no 'format' attribute found in any tag. I find 'type=raw' inside of many <device/> tags but it seems strange to me that a RedHat bug report would use such imprecise language so as to confuse the attribute 'type' with one named 'format' so I wonder if a syntax change has occurred and if that has introduced a regression? virsh edit brws-ms-v7-37v.brockley.harte-lyne.ca show this configuration entry for device sr0: 30 <disk type='block' device='cdrom'> 31 <driver name='qemu' type='raw'/> 32 <source dev='/dev/sr0'/> 33 <target dev='hdc' bus='ide'/> 34 <readonly/> 35 <address type='drive' controller='0' bus='1' target='0' unit='0'/> 36 </disk> Despite the inference I draw from the bug report, that format ~= type, one cannot in fact change the driver attribute 'type' to any value other than raw. Any attempt to do so results in this message: unsupported configuration: unknown driver format value 'host_cdrom' Failed. Try again? [y,n,f,?]: Further, the value 'f' is not permitted so one cannot forcibly save the configuration to determine if in fact it might work. Has anyone else run into this? What is the fix? -- *** E-Mail is NOT a SECURE channel *** James B. Byrne mailto:ByrneJB@Harte-Lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3

1 0

documentation of snapshots
by Bill Campbell 06 Feb '14

06 Feb '14

I am looking for documentation on handling snapshots. The main tasks are: 1. Create a snapshot 2. Roll back a snapshot 3. Merge the snapshot into the base to start the cycle over. Currently I've done steps 1 and 2 into a single qcow2 image. I'm running a relatively old version of libvirtd on CentOS 5, libvirt-0.8.2-29.el5_9.1. Thanks. Bill -- INTERNET: bill(a)celestial.com Bill Campbell; Celestial Software LLC URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way Voice: (206) 236-1676 Mercer Island, WA 98040-0820 Fax: (206) 232-9186 Skype: jwccsllc (206) 855-5792 The question is, why are politicians so eager to be president? What is it about the job that makes it worth revealing, on national television, that you have the ethical standards of a slime-coated piece of industrial waste? -- Dave Barry, "On Presidential Politics"

1 0

Problem with lvm disks assigned to kvm guests
by C. L. Martinez 06 Feb '14

06 Feb '14

Hi all, I have a strange problem when I use lvm disks to expose to virtual guests (host is CentOS 6.5 x86_64). If I remove a kvm guest and all lvm disks attached to it, and I create a new kvm with another lvm disks that use the same disk space previously assigned to the previous kvm guest, this new guest sees all partitions and data. Creating new lvm volumes with different names to this new kvm doesn't resolves the problem. Any idea why?? Thanks.

6 10

Hey
by NightLightHosts Admin 29 Jan '14

29 Jan '14

Just want to let you guys know that, although it may have been around for a bit, bringing Xen back to CentOS is awesome and I really appreciate it. I was very disappointed when RedHat dropped support as Xen is awesome. Thanks for the effort!

3 3

Can't create new Xen domains using libvirt on CentOS 6.5
by Jens Pelzetter 28 Jan '14

28 Jan '14

Hello, we have a strange problem on a fresh install of CentOS 6.5. On the server we want to use Xen to host paravirtualised guests (the system has no hardware virtualization support). To manage the domain we would like to use libvirt. Xen and libvirt are set up as described here: http://wiki.centos.org/HowTos/Xen/Xen4QuickStart http://wiki.centos.org/HowTos/Xen/Xen4QuickStart/Xen4Libvirt When we try to create a new domain this does not work. In /var/log/xen/xend.log we have to the following error: [2014-01-28 10:23:02 1651] DEBUG (XendDomainInfo:103) XendDomainInfo.create(['vm', ['name', 'ccm'], ['memory', '1024'], ['maxmem', '1024'], ['vcpus', '1'], ['uuid', 'be62b0d3-4911-137f-210f-9b0948828106'], ['bootloader', '/usr/bin/pygrub'], ['on_poweroff', 'destroy'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['image', ['linux', ['localtime', '0']]], ['localtime', '0'], ['device', ['vbd', ['dev', 'xvda'], ['uname', 'phy:/dev/medusa-vm/ccm'], ['mode', 'w']]], ['device', ['vif', ['mac', '00:16:3e:1c:ee:5b'], ['bridge', 'br0'], ['script', 'vif-bridge'], ['model', 'virtio']]]]) [2014-01-28 10:23:02 1651] DEBUG (XendDomainInfo:2499) XendDomainInfo.constructDomain [2014-01-28 10:23:02 1651] DEBUG (balloon:187) Balloon: 26832188 KiB free; need 16384; done. [2014-01-28 10:23:02 1651] ERROR (XendDomainInfo:2561) (1, 'Operation not permitted') Traceback (most recent call last): File "/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line 2556, in _constructDomain target = self.info.target()) Error: (1, 'Operation not permitted') [2014-01-28 10:23:02 1651] ERROR (XendDomainInfo:488) VM start failed Traceback (most recent call last): File "/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line 473, 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 2567, in _constructDomain raise VmError(failmsg) VmError: Creating domain failed: name=ccm [2014-01-28 10:23:02 1651] ERROR (XendDomainInfo:108) Domain construction failed Traceback (most recent call last): File "/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line 106, in create vm.start() File "/usr/lib64/python2.6/site-packages/xen/xend/XendDomainInfo.py", line 473, 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 2567, in _constructDomain raise VmError(failmsg) VmError: Creating domain failed: name=ccm [2014-01-28 10:23:02 1651] ERROR (SrvBase:88) Request create failed. Traceback (most recent call last): File "/usr/lib64/python2.6/site-packages/xen/web/SrvBase.py", line 85, in perform return op_method(op, req) File "/usr/lib64/python2.6/site-packages/xen/xend/server/SrvDomainDir.py", line 82, in op_create raise XendError("Error creating domain: " + str(ex)) XendError: Error creating domain: Creating domain failed: name=ccm Any help is appreciated. Best regards, Jens Pelzetter

2 2

Xen HVM Networking in 3.10
by Chris Elliott 24 Jan '14

24 Jan '14

Is anyone running lots of Xen HVM guests on a 3.10 Dom0 kernel? We've had a few weird issues where PV guests are fine, but HVM guests are getting < 1Kb/s network throughput. The configuration on the host machine, VIF and inside the VM is fine. CPU and IO is fine too. It only seems to affect servers with Broadcom network chipsets. Rolling back to a 3.4 Dom0 kernel fixes the problem, so its either driver (bnx2?) related or something else. Not sure what to look at next to troubleshoot this as there are no errors anywhere, but if anyone has a test server with a brodcom NIC please can you test? We've had this on 3 production servers now, but I cant really do any more testing on those as they are full of active VMs. Thanks Chris

2 1

Loading a FreeBSD 10 VM on QEMU-KVM..
by Howard Leadmon 22 Jan '14

22 Jan '14

I was trying to load a FreeBSD 10 VM on my CentOS 6.4 machine, and it keeps hanging and not completing the boot. I have FBSD 9.x VM's running just fine, but if I try and load 10.x it's a no go. Attaching to the console using VNC, I see: gPXE (http://etherboot.org) - 00:04.0 C980 PCI2.10 PnP BBS PMM7FC0@20 C980 Booting from DVD/CD... CD Loader 1.2 Building the boot loader arguments Looking up the /BOOT/LOADER... Found Relocating the loader and the BTX That is it, at that point it just hangs. I have tried from 2G RAM to 6G RAM for the VM, and from 1 to 4 CPU's, but no effect. The FreeBSD lists said I should load a newer QEMU-KVM, that there are much newer releases but everything I have seen claims that is not a good idea, that RH does version numbering much differently. Has anyone run into this, or have any ideas on how to get past it, as I would love to load up the newest FBSD and give it a run as well.. --- Howard Leadmon

8 14

DomU > 128GB
by Karanbir Singh 17 Jan '14

17 Jan '14

Hi, Here is an interesting one - what can we do about this ? Great problem to have though, I just want a dom0 > 128G to start with :) - KB -- Karanbir Singh +44-207-0999389 | http://www.karan.org/ | twitter.com/kbsingh GnuPG Key : http://www.karan.org/publickey.asc

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