Whole snapshot chain is lost when the latest snapshot is deleted #9446
Description
ISSUE TYPE
- Bug Report
COMPONENT NAME
Storage
CLOUDSTACK VERSION
4.19.0
4.19.1
4.19.2
main
CONFIGURATION
N/A
OS / ENVIRONMENT
Env with XenServer
SUMMARY
When deleting a snapshot on XenServer, all of its parents will be erased, causing data loss.
STEPS TO REPRODUCE
1. Create a VM
2. Take a volume snapshot (S1).
3. Access the VM and write some data, for example with: dd if=/dev/zero of=test bs=1M count=1000
4. Use sync to make sure data is written to disk
5. Take a second volume snapshot (S2).
6. Delete the last volume snapshot (S2).
EXPECTED RESULTS
Only the last volume snapshot (S2) is deleted.
ACTUAL RESULTS
On the UI, only the last volume snapshot (S2) is deleted. However, actually, the whole snapshot chain is deleted (S2 AND S1). This can be verified directly on storage or through the snapshot_store_ref table. Any operation with the deleted snapshot (S1) will fail.