Bug 1415559

Assigning to Emma for review.

Lucy, I'm putting this back to New until the bug has been fixed.

Moving the target to match the engineering bugs.

Moving back to Assigned now that the bug has been fixed.

Hi Sharon
I have a few questions regarding this feature that I hope you can help me with.
In the original bug that Shahar worked on, the motivation for creating this feature was that VMs created from pools would have the option to behave like VMs created from templates that have been assigned to multiple storage domains...i.e.

"When a VM is created based on such a template its disks
are allocated by default on the least used SD."
 
However, when I look in the current documentation, I'm not sure that even this has been documented. (i.e. that VMs created from templates in multiple SDs will use the least used SD).

Can you please took a look at the current documentation for creating VMs and let me know whether information is currently missing from here too, in addition to the new Pool feature that needs to be documented:

In particular, for Disk Allocation > Target the description says "The storage domain on which the virtual disk is stored. By default, the storage domain is set to the same value as that of the template. "

It does not mention dynamic allocation at all.

Hi Sharon
1. I sent you a mail describing another potential UI/documentation issue whereby the Disk Allocation field doesn't appear when editing a VM that was created based on a template.

2. Can you pls, give me a definition of what exactly is meant by "least used". Is it the disk with the most capacity at the time of VM creation?

(In reply to Emma Heftman from comment #7)
 
> "When a VM is created based on such a template its disks
> are allocated by default on the least used SD."
>  
I don't think this line above is correct. The user can manually choose the target SD for disk allocation (in case of clone option) and the default is to take values from the template - i.e. documentation is correct.
But just to be on the safe side because I'm not 100% sure, please ask someone from storage.

(In reply to Emma Heftman from comment #8)
> 1. I sent you a mail describing another potential UI/documentation issue
> whereby the Disk Allocation field doesn't appear when editing a VM that was
> created based on a template.

I have just answered your mail and copy it here:
AFAIK the "Disk Allocation" option appears only for "new/edit Pool" or "new VM from template" dialogs. 
For editing a VM you can manage its disks via the general subtab->"instance Images" section. 

So I guess the doc is correct because this section does appear only when creating a VM/Pool from a template.
For Editing a VM you can't change the VM's template anyway, so no need to display "Disk Allocation" anymore. 


> 
> 2. Can you pls, give me a definition of what exactly is meant by "least
> used". Is it the disk with the most capacity at the time of VM creation?

"Least used" in terms of SD means the SD with more free space left (you can see the "free space" in "storage domains list" panel in UI

(In reply to Sharon Gratch from comment #9)
> (In reply to Emma Heftman from comment #7)
>  
> > "When a VM is created based on such a template its disks
> > are allocated by default on the least used SD."
> >  
> I don't think this line above is correct. The user can manually choose the
> target SD for disk allocation (in case of clone option) and the default is
> to take values from the template - i.e. documentation is correct.
> But just to be on the safe side because I'm not 100% sure, please ask
> someone from storage.

FYI I checked the behaviour of the system with Idan from the Storage team. The system does not behave as described here - there is either thin provisioned or cloned allocation and neither use optimization.
> 
> (In reply to Emma Heftman from comment #8)
> > 1. I sent you a mail describing another potential UI/documentation issue
> > whereby the Disk Allocation field doesn't appear when editing a VM that was
> > created based on a template.
> 
> I have just answered your mail and copy it here:
> AFAIK the "Disk Allocation" option appears only for "new/edit Pool" or "new
> VM from template" dialogs. 
> For editing a VM you can manage its disks via the general subtab->"instance
> Images" section. 
> 
> So I guess the doc is correct because this section does appear only when
> creating a VM/Pool from a template.
> For Editing a VM you can't change the VM's template anyway, so no need to
> display "Disk Allocation" anymore. 
> 
> 
> > 
> > 2. Can you pls, give me a definition of what exactly is meant by "least
> > used". Is it the disk with the most capacity at the time of VM creation?
> 
> "Least used" in terms of SD means the SD with more free space left (you can
> see the "free space" in "storage domains list" panel in UI

Reviewed and merged.

The documentation is available in the Customer Portal:

https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html-single/administration_guide/#sect-Explanation_of_Settings_and_Controls_in_the_New_Pool_Window