I am not sure but drop index is taking seriously long time on my system. I always thought that it should be a metadata operation and should be done in 1-2 seconds max but it is taking too much time.
I checked for any blocking and there was no blocking.Also, I executed the drop index command putting it in single user mode as well but still it was taking time.
I used mon tables to look at monProcessObject and waits and activity. It was doing logical/physical IO's and index is quite large and it is not in memory and most of waits were type 29. I was wondering why drop index needs to read all the index pages. It is seriously strange.
ASE version is 15.0.3