Re: [Engine-devel] SharedRawDisk feature detail

On 13/02/12 19:44, Maor wrote: > On 02/12/2012 07:03 PM, Livnat Peer wrote: >> On 02/02/12 17:15, Maor wrote: >>> Hello all, >>> >>> The shared raw disk feature description can be found under the following >>> links: >>> http://www.ovirt.org/wiki/Features/DetailedSharedRawDisk >>> http://www.ovirt.org/wiki/Features/SharedRawDisk >>> >>> Please feel free, to share your comments. >>> >>> Regards, >>> Maor >>> _______________________________________________ >>> Engine-devel mailing list >>> Engine-devel(a)ovirt.org >>> http://lists.ovirt.org/mailman/listinfo/engine-devel >> >> Hi Maor, >> >> - "when taking a VM snapshot, a snapshot of the shared disk will not be >> taken." >> I think it is worth mentioning that the shared disk will be part of the >> VM snapshot configuration. The disk will appear as unplugged. > Agreed, I changed it to the following: > when taking a vm snapshot, a snapshot of the shared disk should not be > taken, although it will be part of the VM snapshot configuration and the > disk will appear as unplugged. >> >> - Move VM is deprecated in 3.1. > Right, I removed this anecdote from the wiki. >> >> - It seems from the wiki that shared disk is not supported for template >> but is supported for VM pool. >> I am not sure how can we do that? iirc we create pool from template. > What I was thinking about, is that the administrator can take a VM from > the pool and attach it a shared disk, after the VM was created (for > testing). > > The motivation for adding shared disk was that each entity that can be > added with a disk can also be added with shared disk. > Today, Administrator can add a disk to a VM from pool, which might be > wrong behaviour, so maybe its better not to support it... >> >> What is the complexity of supporting shared disk in Templates? off the >> top of my head it seems like it is more complicated to block shared >> disks in templates than to support it. What do you think? > Implementation wize it might be less complex, the problem is the use > cases it raises, > some of them which I'm thinking about are: > * If the disk will be deleted from the DC, should we remove it from the > template? or leave an indication in the template that there was a shared > disk there, maybe should not allow to delete the disk in the first > place, until it is unattached from the template? Since template configuration is 'read-only' you can not change a disk to be plugged or unplugged. I would say you can not delete a disk that is part of a template regardless if it is shared or not.

> * What do we want to do when creating a template from VM with shared > disk - Should User choose whether to create a template with/without the > shared disk? > If a user is creating a template from VM the configuration should be identical to the VM. > Blocking shared disk from template means creating the template without > the shared disk, the implementation for it is to check if the disk is > shared or not. > I think that if GUI will support attaching shared disk to multiple VMs, > there is no strong use case for allowing adding shared disk to a template. I am not sure what the above comment means but remember that we have API users as well as UI. I think that if we don't have a strong case for not supporting shared disk in templates the default should be to support it. >> >> Livnat >>