Root disk size reverts to its template size after rebuild

[aleskxyz]

ISSUE TYPE

• Bug Report

COMPONENT NAME

Management Server

CLOUDSTACK VERSION

4.13

CONFIGURATION

CloudStack 4.13
vSphere 6.5

OS / ENVIRONMENT

SUMMARY

STEPS TO REPRODUCE

• resize root disk to larger size
• rebuild vm

EXPECTED RESULTS

CloudStack resize root disk to larger size after rebuild

ACTUAL RESULTS

• root disk size reverts to its original template size
• CloudStack reports root disk size has not been reverted

[DaanHoogland]

@aleskxyz what diskoffering did the VM have to begin with?

[aleskxyz]

@aleskxyz what diskoffering did the VM have to begin with?
I have create VM from a template which its root disk is created from a dynamic disk offering.

[aleskxyz]

More investigation results:

Scenario 1:

1. Create a VM with root disk same as template
2. Upgrade root disk
3. Rebuild VM
   Result: root disk size reverts to template size

Scenario 2:

1. Create a VM with increased root disk size
2. Rebuild VM
   Result: root disk size is ok

Scenario 3:

1. Create a VM with increased root disk size
2. Upgrade root disk
3. Rebuild VM
   Result: root disk size is ok

[aleskxyz]

Workaround:
It seems that when you increase root disk size at deployment, CloudStack initializes "rootdisksize" as a variable in "details" list with the size of root disk.
When you request for rebuild, CloudStack looks for "rootdisksize" regardless of its value, and recreates root disk according to its latest size.
So this scenario is a workaround to this bug:

1. Create a VM with root disk same as template
2. Upgrade root disk
3. Call "updateVirtualMachine" by adding "rootdisksize=0" to "details" list.
4. Rebuild VM
   Result: root disk size is ok

[DaanHoogland]

Sounds like this can be done by :

1. Create a VM with root disk same as template
2. (under the hood) Call "updateVirtualMachine" by adding "rootdisksize=0" to "details" list.
3. Upgrade root disk
4. Rebuild VM
   Result: root disk size should be ok

are you planning to fix this @aleskxyz ?

[aleskxyz]

Sounds like this can be done by :

1. Create a VM with root disk same as template
2. (under the hood) Call "updateVirtualMachine" by adding "rootdisksize=0" to "details" list.
3. Upgrade root disk
4. Rebuild VM
   Result: root disk size should be ok

are you planning to fix this @aleskxyz ?

@DaanHoogland
I really want to contribute on CS code but unfortunately I'm not a developer :(

[DaanHoogland]

ok @aleskxyz , unfortunately that means there is no guarantee it will actually be implemented. I will if i find the time but make no promises

[aleskxyz]

Better workaround:
Based on this line of code we can abuse (?!) template details and inject "rootdisksize" in vm details:

By this workaround everything goes as expected.

[DaanHoogland]

@aleskxyz glad it works for you, but now you are tying the rootDiskSize to the template instead of the diskOffering. If this template is never used with a fixed diskOffering 👍 , is it?