Bug 1095808

This is by design - when previewing a snapshot, you preview the disks /included in it/.
The behavior you expect is available by using the custom preview.

This should be documented, and perhaps made more intuitive, but it should not block 3.4.0's release.

Hi Einav/Sean,

The described issue indicates a confusing aspect of previewing a partial snapshot. Currently, when previewing a snapshot that contains a partial sub-set of the VM disks, the resulting Active VM simply contains the same sub-set of disks (at the snapshot point of time). Intuitively, that sub-set of disks can be viewed on 'Snapshots sub-tab -> Disks tab'. However, the raised concern is that the user would expect to get the *entire* set of disks (as prior to single disk snapshot feature [1]).

So, we should probably choose between the following alternatives:
a. Leave the current behavior as is (best of a bad lot?).
b. Open the 'custom preview snapshot' dialog [2] whenever the selected snapshot to preview has a different number of disks than the active VM - probably not consistent enough?
c. Automatically add to the preview snapshot disks form active VM (if they're not part of the selected snapshot) - probably confusing as well?

What do you think?

[1] http://www.ovirt.org/Features/Single_Disk_Snapshot
[2] http://www.ovirt.org/Features/Single_Disk_Snapshot#Screenshot

Created attachment 902593 [details]
mockup: Partial Snapshot Preview

Hi Derez,

I am assuming that these are the popular options:

(i)  The previewed VM should include only disks that are included in the snapshot (this is what happens today).

(ii) The previewed VM should include all of the disks in the current (active) VM: 
disks that are included in the snapshot: should be taken from that snapshot.
disks that are not included in the snapshot: should be taken from the current VM state ("Active VM"). 


so one of the following is probably true (need PM input on that):

(1) option (i) is (expected to be) far more popular than option (ii).

(2) option (ii) is (expected to be) far more popular than option (i).

(3) option (i) and option (ii) are (expected to be) "equally" popular; both options together are  (expected to be) far more popular than any other partial-snapshot-preview option. 

(4) no partial-snapshot-preview option is (expected to be) far more popular than another. 

note that if (3) or (4) are true - we should ask the user what to do, since there isn't a clear popular behavior that we can apply by default (so (a) and (c) are irrelevant solutions in this case). 


in addition to solutions (a), (b), and (c) suggested in Comment #2 - I am suggesting (b'): 
b'. whenever the selected snapshot to preview has a different number of disks than the active VM, open a dialog such as the one mocked-up in attachment 902593 [details]: this dialog lists the popular options, in addition to an option to further customize the preview using [2]. 
I believe that this would be easier for the user, rather than manipulating all choices within the custom-preview-snapshot dialog. 
[BTW - I assume that (i) and (ii) also have a straight-forward 'configuration' and 'memory' default selections that make sense, so we won't need to ask the user specifically about 'configuration' and 'memory' for the first two options in attachment 902593 [details]]


my opinion regarding the solution that needs to be implemented: 

if (1) is true: I am in favor of (a) [i.e. do nothing / close this bug]. 
we can also do (b') or (b), with the popular option (i) selected by default. 

if (2) is true: I am in favor of (c). 
we can also do (b') or (b), with the popular option (ii) selected by default. 

if (3) is true: I am in favor of (b') [nothing selected by default].  
we can also do (b). 

if (4) is true: I am in favor of (b) [nothing selected by default].  


regarding the consistency concern [relevant for (b)/(b')]: 
I personally don't think that it is problematic to open a dialog in only some of the use-cases in a certain flow, even though it may seem inconsistent; we are already doing similar things in some scenarios, e.g. 'Add Host' without configuring Power Management (which results in a confirmation dialog on top of the 'Add Host' dialog), vs. 'Add Host' with Power Management configuration (which doesn't result in that confirmation dialog). 


needinfo'ing @Malini/Eldan if they have any comments/additional suggestions. 


@Sean - any comments/preference/additional information?

[2] http://www.ovirt.org/Features/Single_Disk_Snapshot#Screenshot

Created attachment 907186 [details]
Refined Einav's idea. Reduced text and options. Attached is the solution.

Refined Einav's idea.
Reduced text and options.
Attached is the solution.

(In reply to Eldan Hildesheim from comment #5)
> Created attachment 907186 [details]
> Refined Einav's idea. Reduced text and options. Attached is the solution.
> 
> Refined Einav's idea.
> Reduced text and options.
> Attached is the solution.

Eldan; this means that the option of including in the previewed-VM only the disks in the selected snapshot (i.e. the first radio button in attachment 902593 [details]) is not easily "accessible". 

So if having *all current VM disks* in the previewed VM is the most popular option [(2) in Comment #4], your proposal is OK.

If having *only the snapshot's disks* in the previewed VM is the most popular option [(1) in Comment #4], the default behavior should be as it is today, and the text in attachment 907186 [details] should change from "The Preview will add them automatically" to "The Previewed VM will not include them". 

If both options above are equally popular, and both of them together are far more popular than any other possible option [(3) in Comment #4], I believe that attachment 902593 [details] is better, as it easily displays both popular options, and not only one of them, as in your suggestion. 

Thanks.

*** Bug 1111983 has been marked as a duplicate of this bug. ***

When unselecting a disk from the custom preview and/or commiting it, there should be a clear warning (perhaps change the color of that disk?) to indicate it will be removed.

(In reply to Einav Cohen from comment #6)

Thanks Einav,

To summarize (and also to keep things simple)

1. The previewed VM should include all of the disks in the current (active) VM by default (should be the first radio button option in the "Partial Snapshot Preview" if you will)

2. Add a clear warning to indicate that unselecting a disk from the custom preview will cause it to be removed.

Thanks
Sean

*** Bug 1148081 has been marked as a duplicate of this bug. ***

I tested this in V3.5 vt7 and the new solution is more intuitive. Moving to Verified

Please supply doc text

RHEV-M 3.5.0 has been released, closing this bug.