CentOS virt - Jul 2011 - how to add file-based disk space to a guest

hi there,

I'm following these documentations to add a file-based disk volume to
a KVM guest under Centos 6.0 :
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/chap-Virtualization-Storage_Volumes.html

as instructed, I created a "pool" then a "volume",
file-based, e.g :

mkdir /mnt/raid/kvm_pool1
virsh # pool-define-as pool1 dir - - - - "/mnt/raid/kvm_pool1"
virsh # pool-autostart pool1
virsh # vol-create-as pool1 volume1 20G --allocation 15G --format qcow2

now I want to associate "volume1" to my guest OS. Following this doc:

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/sect-Virtualization-Virtualized_block_devices-Adding_storage_devices_to_guests.html

- why does this ask me to create a file with "dd" ? it's already
been
created before with the virsh pool commands, isn't it? Seems to
me I'm bypassing the libvirt/virsh layer if I do that.

- after that, the doc tells me to do some stuff with guest XML files.
Is'nt there some specific commands provided by
virsh to associate a managed Pool to a managed Guest ?

- in this case, should I use the virsh "attach-disk" command ?

thanks.
--
Tom

anyone may help on that topic ?
thanks

2011/7/20 thomas veymont <thomas.veymont at
gmail.com>:
> hi there,
>
> I'm following these documentations to add a file-based disk volume to
> a KVM guest under Centos 6.0 :
>
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/chap-Virtualization-Storage_Volumes.html
>
> as instructed, I created a "pool" then a "volume",
file-based, e.g :
>
> mkdir /mnt/raid/kvm_pool1
> virsh # pool-define-as pool1 dir - - - - "/mnt/raid/kvm_pool1"
> virsh # pool-autostart pool1
> virsh # vol-create-as pool1 volume1 20G --allocation 15G --format qcow2
>
> now I want to associate "volume1" to my guest OS. Following this
doc:
>
>
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/sect-Virtualization-Virtualized_block_devices-Adding_storage_devices_to_guests.html
>
> - why does this ask me to create a file with "dd" ? it's
already been
> created before with the virsh pool commands, isn't it? Seems to
> me I'm bypassing the libvirt/virsh layer if I do that.
>
> - after that, the doc tells me to do some stuff with guest XML files.
> Is'nt there some specific commands provided by
> virsh to associate a managed Pool to a managed Guest ?
>
> - in this case, should I use the virsh "attach-disk" command ?
>
> thanks.
> --
> Tom
>

thanks for your answer,

sure I could use the GUI but I wanted, somehow, to understand
how to do it with the shell commands (useful in some situation).

Tom
>
>Trey Dockendorf treydock at gmail.com
>Tue Jul 26 19:44:06 EDT 2011
>
>I'm not aware of a virsh attach disk command but if you duplicate the
>entries for the existing disk you can then add the new one...something like
>this...
>
># virsh -c qemu:///system edit VMname
>
> ?<disk type='file' device='disk'>
>? ? ?<driver name='qemu' type='qcow2'
cache='none'/>
>? ? ?<source file='/var/lib/libvirt/images/vmname_var.qcow2'/>
>? ? ?<target dev='vda' bus='virtio'/>
>? ? ?<address type='pci' domain='0x0000'
bus='0x00' slot='0x04'
>function='0x0'/>
>? ?</disk>
>
>You will have to adjust the values of course.
>
>Why not try doing this with virt-manager? ?When I started using KVM (after
>moving from ESXi) I had trouble with all the commands and finding everything
>I needed, but virt-manager works great.
>
>- Trey
>
2011/7/20 thomas veymont <thomas.veymont at
gmail.com>:
> hi there,
>
> I'm following these documentations to add a file-based disk volume to
> a KVM guest under Centos 6.0 :
>
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/chap-Virtualization-Storage_Volumes.html
>
> as instructed, I created a "pool" then a "volume",
file-based, e.g :
>
> mkdir /mnt/raid/kvm_pool1
> virsh # pool-define-as pool1 dir - - - - "/mnt/raid/kvm_pool1"
> virsh # pool-autostart pool1
> virsh # vol-create-as pool1 volume1 20G --allocation 15G --format qcow2
>
> now I want to associate "volume1" to my guest OS. Following this
doc:
>
>
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/sect-Virtualization-Virtualized_block_devices-Adding_storage_devices_to_guests.html
>
> - why does this ask me to create a file with "dd" ? it's
already been
> created before with the virsh pool commands, isn't it? Seems to
> me I'm bypassing the libvirt/virsh layer if I do that.
>
> - after that, the doc tells me to do some stuff with guest XML files.
> Is'nt there some specific commands provided by
> virsh to associate a managed Pool to a managed Guest ?
>
> - in this case, should I use the virsh "attach-disk" command ?
>
> thanks.
> --
> Tom
>