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[libvirt-users] using shared storage with libvirt/KVM?
by David Ehle 04 May '10

04 May '10

I apologize if this is a duplicate. I submitted it before I was a list member and it looks like it went into limbo. Dear Moderator, please discard the original if it is sitll in a moderation queue. Hello, I've spent a few days googling and reading documentation, but I'm looking for clarification and advise on setting up KVM/libvirt with shared storage. I have 2 (for now) Ubuntu Karmic systems with KVM/virsh/virt-manager set up and running. I have a storage server that can do NFS/iSCSI/samba/ etc. I am trying to figure out the best way to set things up so that I can run several (eventually) production linux guests (mostly debian stable) on the 2 KVM host systems and be able to migrate them when maintenance is required on their hosts. Performance is of medium importance, stability/availibilty is pretty high priority. A common opinion seems to be that using LVs to hold disk images gives possibly the best IO performance, followed by raw, then qcow2. Would you agree or disagree with this? What evidence can you provide? I am also rather confused about using shared storage, and what options can be combined with this. I have succesfully made an iscsi device available to libvirt/virsh/virt-manager via an XML file + pool-define + pool-start. However the documentation states that while you can create pools through libvirt, volumes have to be pre-allocated: http://libvirt.org/storage.html "Volumes must be pre-allocated on the iSCSI server, and cannot be created via the libvirt APIs." I'm very unclear on what this means in general, and specifically how you preallocate the the Volumes. When I make a iscsi pool available via something like this: <pool type="iscsi"> <name>virtimages</name> <source> <host name="iscsi.example.com"/> <device path="demo-target"/> </source> <target> <path>/dev/disk/by-path</path> </target> </pool> In virt-manger I can see it as a pool, but when I try to select it for where to create an image, it uses the pool AS A Volume (I think). That brings me to my next question/misunderstanding... If you are using shared storage (via NFS or iSCSI) does that also mean you MUST use a file based image rather than an LVM LV? NFS makes directories available, not devices. You can make an unformated "raw" LV available via iSCSI, but its not seen on the far side as a LV but instead as a scsi disk which you need to partition. You can make a PV>VG>LV out of that and then make your new LV available to libvirt/KVM but then your stacking a heck of a lot of LVM/LVs/partion tables up which seems pretty dubious. I'm also not sure that the stack would be visable/available to the second system using that iSCSI device. (I'm pretty new to using iSCSI as well.) Redhat provides pretty good documentation on doing shared storage/live migration for NFS: http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Virtuali… But unfortunately the section on Shared Storage with iSCSI is a bit lacking: "9.1. Using iSCSI for storing guests This section covers using iSCSI-based devices to store virtualized guests." and thats it. For maybe 6-10 guests, should I simply just be using NFS? Is its performance that much worse than iSCSI for this task? So since KVM/libvirt is getting used quite often in production now - but some simple things are not making any sense to me - I'm guessing that I have some really basic misunderstandings of how to do shared storage / Pools/ Volumes for migration. Would one of the kind readers of this least be willing to correct me? Please CC to my original email address as well as I am not yet a regular subscriber. Thanks again! David.

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[libvirt-users] Issues after migrating from Xen to KVM
by Ralf Hornik Mailings 04 May '10

04 May '10

Dear list, I have moved my HVMs from xen to kvm and it worked well except some problems using virsh. First, one OpenSolaris HVM does boot with warnings: WARNING: /pci@0,0/pci1af4,1100@1,2 (uhci1): No SOF interrupts have been received, this USB UHCI host controller is unusable* *The corresponding process: /usr/bin/qemu-system-x86_64 -S -M pc-0.12 -enable-kvm -m 1024 -smp 1,sockets=1,cores=1,threads=1 \ -name server01 -uuid e382c360-23bd-b400-0b89-9a1e69613ec4 -nographic \ -nodefaults -chardev socket,id=monitor,path=/usr/local/libvirt/var/lib/libvirt/qemu/server01.monitor,server,nowait \ -mon chardev=monitor,mode=readline -rtc base=utc -boot c -drive file=/dev/xen_vol/xen_opensol,if=none,id=drive-ide0-0-0,boot=on \ -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive file=/dev/hde,if=none,id=drive-ide0-0-1 \ -device ide-drive,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1 -device rtl8139,vlan=0,id=net0,mac=00:16:3e:28:85:7a,bus=pci.0,addr=0x4 \ -net tap,ifname=tap0,vlan=0,name=hostnet0 -chardev pty,id=serial0 -device isa-serial,chardev=serial0 -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3 This does not happen when I boot with plain qemu-bin: /usr/local/kvm/bin/qemu-system-x86_64 -hda /dev/xen_vol/xen_opensol \ -hdb /dev/hde -net nic,macaddr=00:16:3e:28:85:7a \ -net tap,ifname=tap0 -nographic \ -m 1024 -daemonize Second is one Centos 5.2 HVM that does not boot at all. However when I boot manually and omitt "-S" and "-nodefaults" then it comes up. I looked for the -S option and I wonder why it is being used by default. Can anybody help me? I cannot see any further documentation about the "-nodefault" option and how to disable "-S" Best regards Ralf

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Re: [libvirt-users] Windows Vista Client Fails to Connect to Ubuntu libvirtd
by Matthias Bolte 03 May '10

03 May '10

2010/4/30 Tim McLeod <tim.mcleod(a)simulamen.eu>: > Requesting urgent assistance if I may? > > Attempting to connect to an Ubuntu machine using an MinMG compiled virsh on > a Windows Vista machine. Using insecure TCP simply to prove a concept to a > client. However, cannot connect; situation as follows: > > Edited /etc/libvirt/libvirt.conf as follows: > listen_tcp = 1 > auth_tcp = "none" > > Edited /etc/default//libvirt-bin as follows: > libvirt-opts="-d -l" Did you restart libvirtd after the changes and checked that it's started successfully? listen_tls defaults to 1 in /etc/libvirt/libvirt.conf, in combination with the -l flag (short for --listen) libvirtd requires properly configured SSL certificates. If libvirtd can't find the certificates or fails to validate them then it won't start up. You can disable TLS in /etc/libvirt/libvirt.conf by setting listen_tls = 0 and restart libvirtd. > Running virsh on Vista client fails as follows: > $ virsh -c qemu+tcp://192.168.1.101/system > error: unable to connect to libvirtd at '192.168.1.101': errno=10061 > error: failed to connect to the hypervisor > > Running virsh on Ubuntu server fails as follows: > $ virsh -c qemu+tcp:///system > Connecting to uri: qemu+tcp:///system > error: unable to connect to libvirtd at 'localhost': Connection refused > error: failed to connect to the hypervisor Once libvirtd is running and configured properly for TCP transport then remote and local TCP access to libvirtd works for me. > Indeed, with libvirt-opts="-d -l" in etc/default//libvirt-bin the 'default' > command also fails: > $ virsh -c qemu:///system > Connecting to uri: qemu:///system > error: unable to connect to 'var/run/libvirt/libvirt-sock': Connection > refused > error: failed to connect to the hypervisor > Local access to libvirtd using qemu:///system requires properly configured polkit, or running virsh as root. This is independent from the -d and -l flags. Matthias

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[libvirt-users] Windows Vista Client Fails to Connect to Ubuntu libvirtd
by Development 01 May '10

01 May '10

Requesting urgent assistance if I may? Attempting to connect to an Ubuntu machine using an MinMG compiled virsh on a Windows Vista machine. Using insecure TCP simply to prove a concept to a client. However, cannot connect; situation as follows: Edited /etc/libvirt/libvirt.conf as follows: listen_tcp = 1 auth_tcp = "none" Edited /etc/default//libvirt-bin as follows: libvirt-opts="-d -l" Running virsh on Vista client fails as follows: $ virsh -c qemu+tcp://192.168.1.101/system error: unable to connect to libvirtd at '192.168.1.101': errno=10061 error: failed to connect to the hypervisor Running virsh on Ubuntu server fails as follows: $ virsh -c qemu+tcp:///system Connecting to uri: qemu+tcp:///system error: unable to connect to libvirtd at 'localhost': Connection refused error: failed to connect to the hypervisor Indeed, with libvirt-opts="-d -l" in etc/default//libvirt-bin the 'default' command also fails: $ virsh -c qemu:///system Connecting to uri: qemu:///system error: unable to connect to 'var/run/libvirt/libvirt-sock': Connection refused error: failed to connect to the hypervisor Suggestions very welcome... Tim McLeod

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[libvirt-users] Windows Vista Client Fails to Connect to Ubuntu libvirtd
by Tim McLeod 01 May '10

01 May '10

Requesting urgent assistance if I may? Attempting to connect to an Ubuntu machine using an MinMG compiled virsh on a Windows Vista machine. Using insecure TCP simply to prove a concept to a client. However, cannot connect; situation as follows: Edited /etc/libvirt/libvirt.conf as follows: listen_tcp = 1 auth_tcp = "none" Edited /etc/default//libvirt-bin as follows: libvirt-opts="-d -l" Running virsh on Vista client fails as follows: $ virsh -c qemu+tcp://192.168.1.101/system error: unable to connect to libvirtd at '192.168.1.101': errno=10061 error: failed to connect to the hypervisor Running virsh on Ubuntu server fails as follows: $ virsh -c qemu+tcp:///system Connecting to uri: qemu+tcp:///system error: unable to connect to libvirtd at 'localhost': Connection refused error: failed to connect to the hypervisor Indeed, with libvirt-opts="-d -l" in etc/default//libvirt-bin the 'default' command also fails: $ virsh -c qemu:///system Connecting to uri: qemu:///system error: unable to connect to 'var/run/libvirt/libvirt-sock': Connection refused error: failed to connect to the hypervisor Suggestions very welcome... Tim McLeod

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[libvirt-users] using shared storage with libvirt/KVM?
by David Ehle 01 May '10

01 May '10

Hello, I've spent a few days googling and reading documentation, but I'm looking for clarification and advise on setting up KVM/libvirt with shared storage. I have 2 (for now) Ubuntu Karmic systems with KVM/virsh/virt-manager set up and running. I have a storage server that can do NFS/iSCSI/samba/ etc. I am trying to figure out the best way to set things up so that I can run several (eventually) production linux guests (mostly debian stable) on the 2 KVM host systems and be able to migrate them when maintenance is required on their hosts. Performance is of medium importance, stability/availibilty is pretty high priority. A common opinion seems to be that using LVs to hold disk images gives possibly the best IO performance, followed by raw, then qcow2. Would you agree or disagree with this? What evidence can you provide? I am also rather confused about using shared storage, and what options can be combined with this. I have succesfully made an iscsi device available to libvirt/virsh/virt-manager via an XML file + pool-define + pool-start. However the documentation states that while you can create pools through libvirt, volumes have to be pre-allocated: http://libvirt.org/storage.html "Volumes must be pre-allocated on the iSCSI server, and cannot be created via the libvirt APIs." I'm very unclear on what this means in general, and specifically how you preallocate the the Volumes. When I make a iscsi pool available via something like this: <pool type="iscsi"> <name>virtimages</name> <source> <host name="iscsi.example.com"/> <device path="demo-target"/> </source> <target> <path>/dev/disk/by-path</path> </target> </pool> In virt-manger I can see it as a pool, but when I try to select it for where to create an image, it uses the pool AS A Volume (I think). That brings me to my next question/misunderstanding... If you are using shared storage (via NFS or iSCSI) does that also mean you MUST use a file based image rather than an LVM LV? NFS makes directories available, not devices. You can make an unformated "raw" LV available via iSCSI, but its not seen on the far side as a LV but instead as a scsi disk which you need to partition. You can make a PV>VG>LV out of that and then make your new LV available to libvirt/KVM but then your stacking a heck of a lot of LVM/LVs/partion tables up which seems pretty dubious. I'm also not sure that the stack would be visable/available to the second system using that iSCSI device. (I'm pretty new to using iSCSI as well.) Redhat provides pretty good documentation on doing shared storage/live migration for NFS: http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Virtuali… But unfortunately the section on Shared Storage with iSCSI is a bit lacking: "9.1. Using iSCSI for storing guests This section covers using iSCSI-based devices to store virtualized guests." and thats it. For maybe 6-10 guests, should I simply just be using NFS? Is its performance that much worse than iSCSI for this task? So since KVM/libvirt is getting used quite often in production now - but some simple things are not making any sense to me - I'm guessing that I have some really basic misunderstandings of how to do shared storage / Pools/ Volumes for migration. Would one of the kind readers of this least be willing to correct me? Please CC to my original email address as well as I am not yet a regular subscriber. Thanks again! David.

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[libvirt-users] attach-device broken?
by steven765＠yahoo.com 30 Apr '10

30 Apr '10

Hi, Just installed a new FC12 box with all new updates. Figured out to delete the CDROM so the images actually boot now. However, after the upgrade, I can no longer attach my network interfaces to running images? Was this capability removed? Is there some new setting that has to be configured? It's a very simple configuration that hasn't changed and still works on the pre-update box. <interface type='network'> <mac address='52:54:00:58:9c:00'/> <source network='mynetwork'/> yes it's defined and active </interface> Thanks in advance, Steve

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[libvirt-users] Ignoring invalid update watch -1
by jeremy avnet 30 Apr '10

30 Apr '10

Hello, I've started to get these in my logs every now and then: libvirtd: 18:50:29.792: warning : virEventUpdateHandleImpl:149 : Ignoring invalid update watch -1 What does it mean? Thanks! .:. jeremy

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[libvirt-users] libvirt client certificate location
by Vadym Chepkov 30 Apr '10

30 Apr '10

Hi, I was really surprised to find that location of client certificate, key and CA is hardcoded into libvirt. What if I need to manage servers with certificates issued by different CA? Or why do everybody has to use the same private key? Doesn't make it much of a private. It seems so strange I wonder if I am mistaken and it is possible to provide alternative location for the CA, key and certificate? Thank you, Vadym Chepkov

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Re: [libvirt-users] Windows Client
by Matthias Bolte 30 Apr '10

30 Apr '10

2010/4/28 Tim McLeod <tim.mcleod(a)simulamen.eu>: > Having newly compiled a Libvirt on a Windows Vista machine (many thanks to > Matthias Bolte) Nine :) > I have attempted to connect to a remote Ubuntu machine using > virsh.exe. However, the connection fails as follows: > > > > $ virsh -c qemu+tcp:///system You need to specify the server in this URI using a hostname or IP address: qemu+tcp://ubuntu-server.com/system > error: unable to connect to libvirtd at 'localhost': errno=10061 > > error: failed to connect to the hypervisor > > > > 1. I have modified /etc/libvirt/libvirt.conf to set listen_tcp=1. You also need to change this #auth_tcp = "sasl" to auth_tcp = "none" to disable SASL authentication/encryption for TCP connections, because your libvirt on Windows is compiled without SASL support. If you need the libvirt connections to be encrypted you can switch from TCP to TLS connections using: qemu+tls://ubuntu-server.com/system > 2. I cannot find /etc/sysconfig/libvirtd so I am unable to set > LIBVIRTD_ARGS="--listen". > For Ubuntu packaged libvirt see /etc/default/libvirt-bin and change libvirtd_opts="-d" to libvirtd_opts="-d -l" as the comment suggest and restart libvirtd using /etc/init.d/libvirt-bin restart Now you should be able to connect to the libvirtd on your Ubuntu server. Matthias

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