Optimizing the Index generally requires up to three times the amount of disk space as the Index currently uses. Many times this drive space is not available and an alternative method must be employed.
When manually Optimizing the Index from a command line (see SOL61162 for procedure) you have additional options to redirect the Optimization working folder to a different location. This location will be used to house the Index files while they are being Optimized and this will be the location that uses drive space.
The options are:
An example would be:
"Archive Full Text Index Service.exe" –optimize –skipmsg –attoptpath E:\optatt
"Archive Full Text Index Service.exe" –optimize –skipatt –msgoptpath E:\optmsg
"Archive Full Text Index Service.exe" –optimize –attoptpath E:\optatt –msgoptpath E:\optmsg
Also reference these Solutions: