Re: [libvirt] How to get the real device in guest os after attached a disk?
On Tue, Jul 17, 2012 at 4:40 AM, Wangpan <hzwangpan@corp.netease.com> wrote:
I have a question as the subject above, the reason I want to know this is that, if I attach some disks on the guest, for example, I specified /dev/vdc&/dev/vdd(target device) at the cmd line by using 'virsh attach-disk', but they may be /dev/vdb&/dev/vdc in the guest os, so if the guest user want to detach the /dev/vdb(guest device), he\she will be confused with the two target devices /dev/vdb&/dev/vdc, because he\she doesn't know the corresponding relation of the guest device and target device, he\she may detach an error device /dev/vdd(target device) which corresponding to /dev/vdc(guest device).
Could anyone give me some idea?
You can use the virtio-blk serial or file system/volume labels to distinguish them. For libvirt disk <serial> information, see the Domain XML documentation: http://libvirt.org/formatdomain.html#elementsDisks Stefan
Thanks Stefan, But how can I get the serial info in the guest os? I have tried 'hdparm', 'sdparm', 'lshw', 'smartctl' and failed finally. for example, root@debian:~# hdparm -i /dev/vdc /dev/vdb: HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device HDIO_GET_IDENTITY failed: Inappropriate ioctl for device The XML be attached is: <disk type='block' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source dev='/dev/nbd1'/> <target dev='vdc' bus='virtio'/> <serial>WD-WMAP9A966149</serial> <alias name='virtio-disk2'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' function='0x0'/> </disk> The kernel info: root@debian:~# uname -a Linux debian 2.6.32-5-amd64 #1 SMP Mon Jan 16 16:22:28 UTC 2012 x86_64 GNU/Linux
On Tue, Jul 17, 2012 at 4:40 AM, Wangpan <hzwangpan@corp.netease.com> wrote:
I have a question as the subject above, the reason I want to know this is that, if I attach some disks on the guest, for example, I specified /dev/vdc&/dev/vdd(target device) at the cmd line by using 'virsh attach-disk', but they may be /dev/vdb&/dev/vdc in the guest os, so if the guest user want to detach the /dev/vdb(guest device), he\she will be confused with the two target devices /dev/vdb&/dev/vdc, because he\she doesn't know the corresponding relation of the guest device and target device, he\she may detach an error device /dev/vdd(target device) which corresponding to /dev/vdc(guest device).
Could anyone give me some idea?
You can use the virtio-blk serial or file system/volume labels to distinguish them.
For libvirt disk <serial> information, see the Domain XML documentation: http://libvirt.org/formatdomain.html#elementsDisks
Stefan
On Wed, Jul 18, 2012 at 5:01 AM, Wangpan <hzwangpan@corp.netease.com> wrote:
But how can I get the serial info in the guest os?
General documentation on persistent block device naming (just grabbed the first useful link of Google): https://wiki.archlinux.org/index.php/Persistent_block_device_naming If your guest is recent enough it will automatically show the virtio-blk device in /dev/disk/by-id. If not, you may be able to check /sys/block/vda/serial yourself. If that file is not present either your guest doesn't support virtio-blk serial: either upgrade to a newer guest OS version or use one of the other persistent naming mechanisms explained in the link above. Stefan
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Stefan Hajnoczi -
Wangpan