On 09/19/2014 04:01 AM, Yu Xin Huo wrote:

I tried it again today and found below:

1. I can create 2 templates with the same volume of iSCSI storage pool.
2. I can create 2 guests with the same template configured against a volume of iSCSI storage pool.

I think both the design and implementation have problems

1. For template, as it need to be used to create multiple guests, resources there must be collection like network/storage pool, should not be a volume.
2. As volume need to support both read/write, we need to avoid 2 guests use the same volume as boot disk.

Recommended design:

1. In template, when edit, only list storage pool, remove iscsi pool volumes there.
2. When create guest, once user selected the template, if it is iscsi, add a section with a dropdown list for user to select volume, for volume already in use, filter them out.

Only to make everyone aware:

I think we continue using this approach (user selects pool and volume on template) but while creating the VM we need to add the disk as shareable.
So all incoming VMs can make use of the same disk without problems

On 9/19/2014 10:48 AM, Aline Manera wrote:

On 09/18/2014 08:07 AM, Yu Xin Huo wrote:

I got a iSCSI target to work on my redhat with a USB disk to test iSCSI storage pool and found below:

1. When create a iSCSI storage pool, I selected a target in dropdown list.
2. Once the pool is created, I see a volume named 'unit:0:0:1'.
3. When edit template, in the 'storage pool' dropdown, 'unit:0:0:1' is listed there.

So 'unit:0:0:1' which indeed is a volume but listed as a pool in template? or something I am misunderstanding?

The "Storage pool" on Template represents where the guest disk will be created.
So if I specify "default" pool and size 10GB my guest will have a 10GB disk created on the default pool (under /var/lib/libvirt/images, for example)

But it is not true for iSCSI and SCSI pools.
We call the iSCSI and SCSI pools as read-only because we can not create new files on it.
The volumes are pre-configured by the system. Because that while using those pools you also need to select the volume as are represented by <pool_name>/<vol_name> in the combo box.

When a iSCSI or SCSI pool/volume is selected on Template the user can not edit its size, as the volume already exists and has a size.