May 2010 - Users - libvirt List Archives

[libvirt-users] Better error codes when stopping a VM that is already stopped
by Guido Winkelmann 30 Jun '10

30 Jun '10

Hi, Sometimes when stopping a virtual domain using virDomainDestroy(), I come across a domain that is already stopped. (For example when someone already stopped the domain manually using virsh or because the guest OS issued a shutdown.) This is a special case that I absolutely need to catch and handle. Unfortunately, when this happens, and I call virGetLastError() afterwards, I always just get the error code VIR_ERR_OPERATION_INVALID, which doesn't look very precise to me... Two questions about this: Is the domain not running at that moment the only possible condition that can trigger this particular error code when calling virDomainDestroy()? Can't we have a more obvious/precise error code in that case, like VIR_ERR_DOMAIN_NOT_RUNNING or something like that? Guido Winkelmann

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[libvirt-users] Working example of logical storage pool and volume creation?
by Justin Clift 02 Jun '10

02 Jun '10

Hi all, Does anyone have a working example of creation of a logical storage pool and volume? I'm hitting a wall getting logical volumes to work on RHEL 6 beta. There's a single drive I'm trying to setup (sdc) as a libvirt managed logical storage pool, but all volume creation on it fails. Here's what I'm finding so far: Prior to any storage pool work, only the host boot drive (sda) is in lvm. # vgs VG #PV #LV #SN Attr VSize VFree vg_host2 1 3 0 wz--n- 465.27g 0 # pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_host2 lvm2 a- 465.27g 0 # ls -la /dev/mapper total 0 drwxr-xr-x. 2 root root 120 Jun 1 03:12 . drwxrwxrwt. 21 root root 3920 Jun 1 03:12 .. crw-rw----. 1 root root 10, 58 May 31 14:08 control lrwxrwxrwx. 1 root root 7 May 31 14:10 vg_host2-lv_home -> ../dm-7 lrwxrwxrwx. 1 root root 7 May 31 14:08 vg_host2-lv_root -> ../dm-0 lrwxrwxrwx. 1 root root 7 May 31 14:10 vg_host2-lv_swap -> ../dm-8 # Creation of a logical storage pool, using sdc: # virsh pool-define-as guest_images_lvm logical - - /dev/sdc libvirt_lvm /dev/mapper Pool guest_images_lvm defined # virsh pool-info guest_images_lvm Name: guest_images_lvm UUID: 17398035-8000-7252-ab25-58db95aed130 State: inactive # virsh pool-build guest_images_lvm Pool guest_images_lvm built # The physical device and volume group are seen in lvm: # pvs PV VG Fmt Attr PSize PFree /dev/sda2 vg_host2 lvm2 a- 465.27g 0 /dev/sdc libvirt_lvm lvm2 a- 465.76g 465.76g # vgs VG #PV #LV #SN Attr VSize VFree libvirt_lvm 1 0 0 wz--n- 465.76g 465.76g vg_host2 1 3 0 wz--n- 465.27g 0 # Starting the logical pool works: # virsh pool-start guest_images_lvm Pool guest_images_lvm started # Creation of volumes fail: # virsh vol-create-as guest_images_lvm volume1 8G error: Failed to create vol volume1 error: internal error '/sbin/lvcreate --name volume1 -L 8388608K /dev/mapper' exited with non-zero status 3 and signal 0: Volume group name expected (no slash) Run `lvcreate --help' for more information. # So, it looked like "/dev/mapper" in the pool-define-as command should have instead been the LVM volume group again. That doesn't work either though: # virsh pool-define-as guest_images_lvm logical - - /dev/sdc libvirt_lvm libvirt_lvm Pool guest_images_lvm defined # virsh pool-build guest_images_lvm Pool guest_images_lvm built # virsh pool-start guest_images_lvm Pool guest_images_lvm started # virsh vol-create-as guest_images_lvm volume1 8G error: Failed to create vol volume1 error: cannot read path 'libvirt_lvm/volume1': No such file or directory Looking in the libvirtd logs for this last attempt, the volume was actually successfully created. But libvirtd then checks for it's presence (wrongly!), doesn't find it, and then lvremove's it: 03:01:24.000: debug : virRunWithHook:832 : /sbin/lvcreate --name volume1 -L 8388608K libvirt_lvm ... 03:01:24.223: debug : virRunWithHook:848 : Command stdout: Logical volume "volume1" created ... 03:01:24.223: error : virStorageBackendLogicalCreateVol:616 : cannot read path 'libvirt_lvm/volume1': No such file or directory ... 03:01:24.223: debug : virRunWithHook:832 : /sbin/lvremove -f libvirt_lvm/volume1 Guessing I'm either doing something wrong, or hitting bugs, or ? Anyone have ideas/suggestions/etc? Regards and best wishes, Justin Clift -- Salasaga - Open Source eLearning IDE http://www.salasaga.org

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[libvirt-users] Mount options for fs type storage pools?
by Justin Clift 02 Jun '10

02 Jun '10

Hi all, Presently writing up "Storage Pool" docs for the Fedora Virtualisation Guide. (using both virsh and virt-manager) Having trouble finding out how to specify mount options for fs type storage pools. For example: # virsh pool-define-as guest_images_fs fs - - /dev/sdc1 - "/guest_images" Pool guest_images_fs defined # virsh pool-build guest_images_fs Pool guest_images_fs built # virsh pool-start guest_images_fs Pool guest_images_fs started # mount | grep guest_images /dev/sdc1 on /guest_images type ext4 (rw) # Notice that /guest_images is mounted with default options. Nothing wrong with that, but lets say the SysAdmin has a need to pass specific mount options. (ie journal_checksum, or noatime, or nodiratime, etc) Checked the virStorageBackendFileSystemMount() function in present git master, and it doesn't look like mount options are considered for anything other than Gluster? How to do it, or is it best to not use libvirt to manage the mounting of this type of storage when options are needed? Regards and best wishes, Justin Clift -- Salasaga - Open Source eLearning IDE http://www.salasaga.org

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[libvirt-users] Host should not touch passed-through USB device, how?
by Andreas Ntaflos 01 Jun '10

01 Jun '10

Hello list, this may be off topic but it is closely related to my Libvirt adventures so maybe you can help me. I want to pass a USB device (a USB Huawei E620 modem) through to a KVM guest. Pass-through in general works fine and the modem is visible in the guest. However, the host still sees it and sometimes tries to access it (such modems seem to also be USB storage devices). This naturally leads to conflicts and I believe this crashed the guest very badly yesterday. So I am looking for a way to make sure the host passes through the USB device (in its entirety) without trying to touch it and claim it as its own. Preferably without disabling the USB storage subsystem completely on the host. Any ideas? Is there a best practice for such things in the Libvirt world? Or any other world? Thanks! Andreas -- Andreas Ntaflos GPG Fingerprint: 6234 2E8E 5C81 C6CB E5EC 7E65 397C E2A8 090C A9B4

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[libvirt-users] Qemu driver not supporting VIR_DOMAIN_DEVICE_MODIFY_CONFIG yet?
by Guido Winkelmann 01 Jun '10

01 Jun '10

Hi, According to the docs on http://libvirt.org/html/libvirt-libvirt.html#virDomainDetachDeviceFlags I ought to be able to do virDomainDetachDeviceFlags( <domain>, <devicexml>, VIR_DOMAIN_DEVICE_MODIFY_LIVE | VIR_DOMAIN_DEVICE_MODIFY_CONFIG); to detach a volume both from a currently running VM instance and permanently from the defined config file. If I actually try that, though, I'm getting this error: libvir: QEMU error : Requested operation is not valid: cannot modify the persistent configuration of a domain The same thing happens whether or not the domain is running and also happens if I leave out the "VIR_DOMAIN_DEVICE_MODIFY_LIVE" part. Does the qemu driver simply not support VIR_DOMAIN_DEVICE_MODIFY_CONFIG yet (libvirt 0.8.1), or is there some other problem here? Guido

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[libvirt-users] Monitoring KVM Machine Uptimes
by Karsten Knese 01 Jun '10

01 Jun '10

Hey folks. Currently, I am working on an accounting-solution for Private Cloud with Eucalyptus as my bachelor-thesis. Eucalyptus bases on libvirt providing the KVM machines. Part of the thesis is kind of measurement for the uptimes of each instance in the cloud. As Eucalyptus is based on libvirt, i want to know if there is kind of tool already setup for monitoring a vm in terms of uptimes, cputimes and disk i/o. If not, can anyone give me a hint, how i could grep these facts? I found a tool called "virt-top" which monitors the vm, but for me there is to much overhead. Thanks for you support. cheers, Karsten

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[libvirt-users] ballooning option xml
by udo1 01 Jun '10

01 Jun '10

Hi everybody, I need the ballooning option with kvm using libvirt xml file and virsh (virsh create domain.xml) kvm line must be appended with the -balloon virtio switch to enable ballooning. (can be disabled if there no option or with -balloon none ) I currently using Ubuntu Lucid How can I define this in the domain xml file, or what need I to do to get this option? is there any option like enabling with <balloon>virtio</balloon> or disabling with <balloon>none</balloon> Thanks in Advance Udo Attila Fischer

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[libvirt-users] Update Libvirt
by Rafael Braga 31 May '10

31 May '10

Hi, I installed the opensuse 11.0 and libvirt version installed is 0.4. But, Nimbus need the version 0.6.3. How do I upgrade? I can't by YAST... thanks! -- Rafael Braga

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[libvirt-users] monitoring kvm machines with libvirt
by Karsten Knese 31 May '10

31 May '10

Hey folks. Currently, i am working on my bachelorthesis. Subject of this thesis is to setup an accounting-solution for the Private Cloud with Eucalyptus. Eucalyptus works with libvirt providing kvm instances. my question is, if i can grep facts like general uptimes, cpu-peaks and disk i/o of each vm with libvirt-tools?! I just found one called virt-top, which monitors each vm, but unfortunately it produces to much overhead. If you should be no tool, can anybody give me a hint, where i best look at to grep these facts? First try is to grep the uptime of each vm by writing a little deamon, checking one time per minute via virsh, if the vm is in state running. But i don't know, if this is best. thanks for your support! cheers, Karsten

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[libvirt-users] VM parameters best practice?
by Guido Winkelmann 31 May '10

31 May '10

Hi, When creating many virtual machines from a template (disk image), you often need to set some different parameters for each vm. Those usually include root passwords and/or ssh public keys for login, ssh Host keys (so that a) not all the VMs have the same host key and b) the user can know the real host key for his vm before connecting for the first time) plus any number of user-defined parameters. IP addresses and hostnames can be set via DHCP. Obviously, some of those parameters need to be treated as confidential, so you cannot just grab them from some FTP server somewhere. In fact, as long as you haven't set any authentication credentials (like an SSL Client Certificate for example) that the vm can use to uniquely and securely identify itself to some server, you cannot securely get any of these parameters over the network. How do people usually solve that sort of problem? What is considered best practice here? Currently, my own plans are to write these parameters to a floppy image, use Unix file permissions to make sure nobody else can read the image, and then hook up that image to a virtual floppy drive in the respective vm. A shell script in the vm template can then read and apply all those parameter at some early stage during the very first boot. Unfortunately, this means mounting the image in the host system, writing the parameters and then unmounting it again - which seems sort of error prone to me in a fully automated environment. (What if two vms are being created simultaneously? What if the script crashes or hangs somewhere between mounting and unmounting the image?) Regards Guido Winkelmann

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