Thanks Mark for the clarifications.
The way you explained most of the action seems to be outside ASE dataserver and at OS level.
In MDA tables there is only one wait event 85 related to backup process.
Action recommended for 85 is brief and directs to investigate other events slowing down backup.
Will capturing any MDA table data help
Or
I need to ask Unix Admins to watch/collect performance data during the backup window on the host.
Avinash