Unity 400 drowning in snapshots

Hi, I have the following problem with a Unity 400:

For testing I had created a hourly snapshot schedule for several volumes. This Unity is used as target for async replication. After a while I have noticed that the unity wasn't able to delete the numerous snapshots fast enough.

At that moment all space of the pool had been consumed. I have stopped all snapshot creation immediately.

Since then the Unity is trying to delete all the snapshots but any progress is not visible. I have tried to delete one volume to free up space, but also the deletion of that volume is stuck a 1%.

All snapshots have the state 'destroying' since two weeks now.

Any ideas?