Block use of internal and external snapshots on KVM

[JoaoJandre]

Description

On KVM, there are two types of snapshots: internal and external. Most snapshot/backup solutions use external snapshots on ACS; save for disk-and-memory VM snapshots, which use internal snapshots (this is a limitation with KVM, as far as I know).

However, since internal snapshots are stored inside the VM's volume (hence the name), if an internal snapshot is taken after an external snapshot and the external snapshot is restored, the internal snapshot is lost.

Thus, this PR blocks the use of disk-and-memory VM snapshots alongside volume snapshots, NAS backups, and disk-only VM snapshots (at least the ones created using the default volume snapshot implementation).

I encourage maintainers of 3rd party storage providers to test if their implementation is compatible with disk-and-memory VM snapshots, if it is not it their simultaneous usage should be blocked.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

I created a VM and created a few disk-and-memory VM snapshots on it; then I tried to create NAS backups, volume snapshots and disk-only VM snapshots, all of them gave me an error, which is expected.

I validated that the opposite was also true for the aforementioned cases, e.g., create volume snapshot and try to create disk-and-memory VM snapshot.

I also validated that it was possible to create multiple NAS backups, disk-only VM snapshots and volume snapshots with no issues.

[JoaoJandre]

@slavkap @rp- I think it would be interesting to validate if the implementations done for Storpool and Linstor are compatible with disk-and-memory VM snapshots.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 4.00%. Comparing base (8f2735a) to head (18112f2).

❗ There is a different number of reports uploaded between BASE (8f2735a) and HEAD (18112f2). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (8f2735a)	HEAD (18112f2)
unittests	1	0

Additional details and impacted files

@@              Coverage Diff              @@
##               4.20   #11039       +/-   ##
=============================================
- Coverage     16.15%    4.00%   -12.16%     
=============================================
  Files          5657      402     -5255     
  Lines        497898    32608   -465290     
  Branches      60374     5789    -54585     
=============================================
- Hits          80435     1305    -79130     
+ Misses       408505    31154   -377351     
+ Partials       8958      149     -8809     

Flag	Coverage Δ
uitests	4.00% <ø> (ø)
unittests	?

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[JoaoJandre]

@blueorangutan package

[blueorangutan]

@JoaoJandre a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 13798

[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 13809

[DaanHoogland]

@JoaoJandre :

08:35:48 [ERROR] /jenkins/workspace/acs-centos8-pkg-builder/dist/rpmbuild/BUILD/cloudstack-4.20.2.0-SNAPSHOT/engine/storage/snapshot/src/test/java/org/apache/cloudstack/storage/vmsnapshot/VMSnapshotStrategyKVMTest.java:32:8: Unused import - org.apache.cloudstack.backup.dao.BackupDao. [UnusedImports]

[JoaoJandre]

@blueorangutan package

[blueorangutan]

@JoaoJandre a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 13818

[DaanHoogland]

@blueorangutan package

[blueorangutan]

@DaanHoogland a [SL] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ debian ✔️ suse15. SL-JID 13826