Thanks much for your quick reply.
The index cache drive size if 450GB. Currently only two folders are taking all the space ( IndexCache/CvIdxDB - 246Gb ,IndexCache/CvIdxLogs - 190GB )
For some reason, the "download" link of index backup report you have given isnt working for me.
I checked the index backup jobs and they have been running fine, no jobs with errors or failures.
I have modified the two settings given in the link below to 5 days and 100000 and ran the index backup jobs, however it didnt help ( gained only <10Gb space) and I see the Index_Restore job was kicking in as well.
I have 10 File system backup jobs waiting/suspended due to no index cache space. Killing all the jobs a running the index backup would help ?
Any ideas are greatly appreciated.
I am also working on expanding the index cache drive but it would take time.