It was just happened after I created the snapshot "installed". This is my output, all my snapshots are still exists.
And maybe I know how this problem happened:
1. I create snapshots "init -> base -> installed" on this CT "ds"(CTID: 301)
2. And this CT "ds"(CTID: 301) is cloned from...
I create a CT named ct0(1000) as my base ct, and it has one snapshot named snap0.
Then I clone a CT named ct1(1001) from ct0 'current' (not from any snapshot),
There are identical snapshot in ct1, the same as ct0, but I DID'T create it manually.
WHEN I DELETE THE snap0 IN ct1, THE SNAPSHOTS IN...