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1608 discussions

VirtIO disk 'leakage' across guests?
by James B. Byrne 16 Jan '12

16 Jan '12

We are in the process of migrating several stand-alone server hosts onto a CentOS-6 kvm virtual host. We also use Webmin to administer our hosts. All of the guests, without exception, have been cloned brom a prototype guest using virt-manager. All of the additional VirtIO disks assigned to some of the guests have been added through virt-manager as well. Recently I have encountered a situation with the development copy of Webmin where I can see an additional VirtIO disk assigned to one guest instance, but not yet added to the lvg of that guest, as an unknown device on different guest. Further, I can see an lv assigned to one guest instance as an lv on a difference guest. The webmin author is aware of this problem and is assiduously trying to determine its cause. My difficulty is answering the question: How is it even possible for an application running under a httpd service on one guest to see anything at all besides the VirtIO storage assigned to that guest? Has anyone else encountered this anomaly? -- *** 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

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Re: [CentOS-virt] VirtIO disk 'leakage' across guests?
by James B. Byrne 16 Jan '12

16 Jan '12

On Mon, January 16, 2012 13:05, James B. Byrne wrote: > How is it even possible for an > application running under a httpd service on one guest to > see anything at all besides the VirtIO storage assigned to > that guest? > > Has anyone else encountered this anomaly? > I just cloned a guest instance. The clone prototype was set up with a single VirtIO disk of 8Gbs, divided into a 500 Mb boot and a ~7.1Gb root partition. The root partition was entirely assigned to the basic vg and two lv were created, one for swap and one for the actual root partition. When the guest was cloned there was only one VirtIO disk of 8 Gb assigned to it and this was cloned and given a new name. When I look at the newly cloned guest instance with pvdisplay this is what I see: # pvdisplay Couldn't find device with uuid umrIn6-Np0c-NC4Z-MuUo-5TBj-IKRE-XBU0De. --- Physical volume --- PV Name /dev/vda2 VG Name vg_vm_centos_6 PV Size 7.32 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 1874 Free PE 0 Allocated PE 1874 PV UUID djM23m-6Yeb-BQ2x-gPh9-ORMt-dX2i-Ou9xBQ --- Physical volume --- PV Name unknown device VG Name vg_vm_centos_6 PV Size 31.25 GiB / not usable 3.97 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 7999 Free PE 0 Allocated PE 7999 PV UUID umrIn6-Np0c-NC4Z-MuUo-5TBj-IKRE-XBU0De When I look at it using vgdisplay then this is what I see: # vgdisplay Couldn't find device with uuid umrIn6-Np0c-NC4Z-MuUo-5TBj-IKRE-XBU0De. --- Volume group --- VG Name vg_vm_centos_6 System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 10 VG Access read/write VG Status resizable MAX LV 0 Cur LV 4 Open LV 2 Max PV 0 Cur PV 2 Act PV 1 VG Size 38.57 GiB PE Size 4.00 MiB Total PE 9873 Alloc PE / Size 9873 / 38.57 GiB Free PE / Size 0 / 0 VG UUID qa6jwq-5gTp-6mMH-IWl9-OrEK-HjWc-pbaFsa What is going on and how do I fix this? The size of the ghost pv (31Gb) is showing up as the size of the clone's vg whereas the pv for the cloned instance is only 8Gb. I am only using virt-manager to manage disk storage for these guests and I have no idea why or how this mismash is happening. Any ideas? -- *** 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

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Centos 6.2 / KVM troubles with network
by Radek Bursztynowski 14 Jan '12

14 Jan '12

Hi, I have installed CentOS 6.2 x86_64 and KVM/Qemu and I have some troubles with network. The first case: ----------------- The configuration is: - CentOS 6.2 (hardware machine) has one Ethernet interface with static IP address (eth0). - Virtual machine has bridge network interface with eth0 interface on CentOS 6.2. This bridge is created using wizard integrated with virt-manager. - Bridge interface on virtual machine receives IP addres from DHCP server. IP address is received well. - All firewalls and SELinux are closed. Virtual machine has no any connection with CentOS 6.2 hardware machine, and CentOS 6.2 has no any connection with virtual machine. But every others machines have all connection with both virtual and CentOS 6.2 machine. The question: Why? The second case: ---------------------- The configuration is: - On CentOS 6.2 (hardware machine) I created bridhe (br0) with eth0 hardware interface. Two situations: + I force two different IP addresses for eth0 and br0 interfaces - there no any connection with this server. So I don't test this case. + I forced one IP addres for both eth0 and br0 interfaces. ifconfig shows that eth0 has no IP address, br0 has IP address. So, I test this case. - I use Red Hat documentation: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html-single/Vi…) - On virtual machine I created bridge connection with br0 interface on CentOS 6.2. - All machines have all connections. - All firewalls and SELinux are closed. NFS server on CentOS 6.2 (hardware machine) doesn't serve exported file system. The questions: 1. Is it proper that eth0 has no IP addres and bridge (br0) interface has? 2. What about my NFS? NFS server worked well before starting virtualization. Who can me help with my troubles? Regards, Radek

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No module named cygvirtmod
by Lars Hecking 12 Jan '12

12 Jan '12

I'm trying to set up a xen guest on a machine that already has a few others running (not set up by me). It fails with the following error: + virt-install -r 512 -n host5 -f /dev/vol0/lvol5 --nographics -p --os-type=linux --os-variant=rhel5 --accelerate -l http://bla -x ks=http://bla/ks.cfg -m MA:CA:DD:RE:SS Traceback (most recent call last): File "/usr/bin/virt-install", line 31, in ? import libvirt File "/usr/lib64/python2.4/site-packages/libvirt.py", line 12, in ? import cygvirtmod as libvirtmod ImportError: No module named cygvirtmod This is a standard CentOS 5.4 x86_64 install, and I have not been able to find a solution on the web.

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centos 6 domU doesn't see all memory?
by Chris Wik 11 Jan '12

11 Jan '12

I'm running CentOS 6 x86_64 domU on CentOS 5 x86_64 dom0 The host is running 2.6.18-238.19.1.el5xen The guest is 2.6.32-220.2.1.el6.x86_64 'xm list' on the host shows 512mb memory allocated. 'free -m' in the guest shows 224mb memory. 'xm mem-set 21 1024' (21 being the domU ID), 'xm list' now shows 1024mb, but in the guest I now see 736mb. Anyone else seeing this? Any ideas on how to fix it? Chris -- Chris Wik Anu Internet Services Ltd www.cwik.ch | www.anu.net

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KVM VM crash under I/O load (e1000 and virtio)
by Ben Clay 09 Jan '12

09 Jan '12

I'm pretty consistently getting crashed KVM VMs under network I/O load when using the e1000 and virtio NIC models, with the follow message in dmesg: qemu-kvm[8785]: segfault at d0 ip 00000031e3200a08 sp 0000000047784080 error 4 in libnvidia-tls.so.285.05.23[31e3200000+3000] qemu-kvm[8791]: segfault at d0 ip 00000031e3200a08 sp 0000000049f89080 error 4 in libnvidia-tls.so.285.05.23[31e3200000+3000] qemu-kvm[8792]: segfault at d0 ip 00000031e3200a08 sp 000000004a78a080 error 4 in libnvidia-tls.so.285.05.23[31e3200000+3000] [<ffffffff8113b41b>] ? newseg+0xf0/0x213 [<ffffffff8113b32b>] ? newseg+0x0/0x213 These VMs are not performing any tasks with their display that I am aware of, and are not assigned GPUs. I'm aware that this isn't the latest nvidia driver, but I guess I don't understand why it's causing the problem in the first place. The same thing also happens when using the virtio block driver under heavy load. Unfortunately this is forcing me to fall back to the default NIC drivers, which are very slow (~120Mbit/s VM<->VM vs ~460Mbit/s with virtio). We're using vanilla kernel 2.6.32, with the following KVM-related packages: kmod-kvm-83-239.el5.centos kvm-qemu-img-83-239.el5.centos kvm-83-239.el5.centos libvirt-0.8.2-22.el5 Here is an example config (you can see where I commented out the model lines, because the VMs won't stay up): <domain type='kvm'> <name>myvm</name> <memory>8388608</memory> <currentMemory>8388608</currentMemory> <vcpu cpuset="0-7">8</vcpu> <os> <type arch='x86_64' machine='rhel5.4.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' cache='none' type='raw'/> <source file='/vm/path/disk.raw'/>  <target dev='vda'/> </disk> <interface type='bridge'> <mac address='mac1'/> <source bridge='br0'/>  </interface> <interface type='bridge'> <mac address='mac2'/> <source bridge='br9'/>  </interface> <serial type='pty'> <source path='/dev/pts/2'/> <target port='0'/> </serial> <console type='pty' tty='/dev/pts/2'> <source path='/dev/pts/2'/> <target port='0'/> </console>  </devices> </domain> Any help would be appreciated! -Ben

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qemu-kvm
by Radek Bursztynowski 06 Jan '12

06 Jan '12

Hi everybody, I am new member at this list but I am not new with CentOS. I use CentOS 5.x till today, but I try CentOS 6.2 now. Regarding virtualization on CentOS 6.2 (i386) I have some problem. I installed all rpm packages joined to CentOS 6.2 and virtualization. When I try to start virt-manager I receive request to install qemu-kvm package. I try to do it accepting virt-manager advice but i can read message that this package is not available. So, I try to install qemu-kvm using yum - still nothing. Next I added additional packages and repositories as follow: epel-release-6-5.noarch.rpm remi-release-6.rpm centos-release-cr-6-0.el6.centos.i686.rpm rpmfusion-free-release-6-0.1.noarch.rpm rpmfusion-nonfree-release-6-0.1.noarch.rpm Still nothing. I visited http://rpmfind.net/linux/rpm2html/search.php?query=qemu-kvm but there are qemu-kvm packages destined for CentOS x86_64. Could anybody advice me where qemu-kvm packages for CentOS 6.2 i386 is placed or what should I to do to fix my problem? Thanks for any help, Radek

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server host keys for kvm clones
by James B. Byrne 05 Jan '12

05 Jan '12

Respecting cloning vm guests, I see in /etc/ssh the following: ssh_host_dsa_key ssh_host_dsa_key.pub ssh_host_key ssh_host_key.pub ssh_host_rsa_key ssh_host_rsa_key.pub Is there a simple script somewhere to regenerate all the server host keys for the new guest after cloning? -- *** 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

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turning off udev for eth0
by James B. Byrne 04 Jan '12

04 Jan '12

I have set up a kvm host and configured a standard clone prototype for generating new guests. One persistent (pun intended) annoyance when cloning is the behaviour of udev with respect to the virtual network interface. The prototype is configured with just eth0 having a dedicated IP addr. When the prototype is cloned udev creates rules for both eth0 and eth1 in the clone. Because eth1 does not exist in the cloned guest one has to manually edit /etc/udev/rules.d/70-persistent-net.rules to get rid of the bogus entries and then restart the clone instance to have the changes take effect. All this does is return the new guest to the prototype eth0 configuration. Is there no way to alter udev's behaviour? Is udev even needed on a server system using virtual hardware? Altering the rules file not a big deal in itself but it adds needless busywork when setting up a new guest. -- *** 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

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iscsi target rescan means connections hang for five seconds
by Dennis Jacobfeuerborn 03 Jan '12

03 Jan '12

Hi, I'm starting to experiment with iscsi based volumes and while this works fine so far I ran into a problem. When I add a LUN to a target and refresh tgtd all i/o to that target seems to hang for five seconds. This is obviously less than ideal if the plan is to use the target for lots of guests. There is also the possibility to create one target with one LUN for each guest disk but that sounds like a management nightmare and the libvirt pool functions become useless. Is there a way to make this less intrusive? How do you guys cope with this issue? Regards, Dennis

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