regression: disk offering strictness not honored when resizing root volume (4.22.0)

[bradh352]

problem

I'm pretty sure this is a regression. I have a compute offering that sets a default disk size of 400G, but also has the root disk size strictness set to false. When a user goes to grow their root disk size they get an error message:

The tool tip clearly states this should be allowed when creating a disk offering:

And I can confirm when evaluating the compute offering that it was configured with false for strictness:

I'm pretty sure this worked for me at one point, but I honestly don't recall the version. Its fairly rare to need to grow a 400G disk.

versions

4.22.0

The steps to reproduce the bug

1. Create compute offering with a root disk of 400G but do NOT enable disk offering strictness.
2. Create a vm instance using the compute offering
3. Attempt to resize the root disk after creation.

What to do about it?

Fix the regression.

[nvazquez]

Hi @bradh352 I have examined the problem and I'm able to reproduce it by setting a ROOT disk size on the compute offering. However, I don't think this is an issue but it is expected by design after the introduction of flexible service offerings: https://cwiki.apache.org/confluence/display/CLOUDSTACK/Flexible+service+offerings (#5008). I have also found a similar issue previously reported explaining this use case is expected: #9380

To address the problem, can you try changing the offering for the volume to a bigger offering?

[bradh352]

So the disk offering strictness is a create-only attribute, and doesn't apply to future modifications? Is this really what is intended to occur? Seems strange to allow a user to create any disk size they want, but not then allow them to increase it later. The assumption was the disk size provided is a 'sane default', but the user can modify as they see fit.

[nvazquez]

@bradh352 in my understanding the disk offering strictness will control if CloudStack should attempt resize operations or not. In case it is enabled, CloudStack won't allow resizing volumes in any case. When it is disabled, CloudStack will attempt the volume resize but there could be two cases: ROOT disk size is set on the offering or not. When the ROOT disk size is not set, I'm able to resize the volume properly, however when it is set (as in this case) then the operation fails and seems to be expected as per: #9428 (comment).

Adding @sureshanaparti @vishesh92 @harikrishna-patnala who have previously worked on it, please advise if my comments are correct

[harikrishna-patnala]

Yes @nvazquez you are right.

The error mentioned here when resize is attempted is because Root disk size is defined in the offering.

[sureshanaparti]

if the compute offering has the root disk size mentioned, then the resize volume is allowed only through the change in the offering. this is unrelated to disk offering strictness. refer #9380 (comment).

[harikrishna-patnala]

@bradh352 I hope we tried to answer you on why that exception came up when a disk size is given in a compute offering.

DiskOffering strictness is used when operator wants users to change or not to change the whole diskoffering of a root disk. If DiskOffering strictness is enabled, then a user cannot change the disk offering of that root disk using the following action in the Volume operations.

There is a bit of flexibility given when it comes to resizing of the volumes. While a disk offering is created, an operator can still chose whether root disk size can be resized or not using below option in the disk offering

The suggested way if an operator wants to have good control on disk parameters of a root disk, is to create a disk offering separately and link it in the compute offering, like below (by disabling "Compute only disk offering") in the compute offering options.

The above details are all about Disk offerings and the strictness details.

In your case, if you want to have disk size (400G) specified in the offering and allow resize, then create a disk offering with disk size 400G and link to a compute offering with keeping the default values (disabled) of "Disk Offering Strictness" in the compute offering and "Disk size strictness" in the disk offering.