This is an internal instance key distinguishing this particular deletion task from any other deletion task that might exist for the same switch/provider pairing. Since a failed deletion can be retried by creating a fresh task, keyInst on this row is part of what tells apart the current retry attempt from a stale, earlier one that may still be sitting in the table. A keyInst value that increments between successive deletion attempts for the same DVS confirms you're looking at the latest retry rather than the original failed one.