The volume that is used for a staging location for backup jobs should meet the following requirements:
 
·         It is local to the media server
 
·         It does not have any file size limitations
 
·         Create a separate backup-to-disk folder specifically for all GRT-enabled backup jobs
 
·         Select the specific backup-to-disk folder you want to use for GRT-enabled backup jobs
 
·         Do not allocate the maximum size for backup-to-disk files
 
·         Calculate your disk space requirements carefully before you assign a low disk space threshold
 
·         Do not fill up a drive that hosts a backup-to-disk folder that is used for GRT operations
 
Additionally, Symantec recommends the following to avoid disk space problems:
 
·         It should not be a system volume
 
·         It should have at least 1 GB of available space
 
Kindly refer to Backup Exec 12.5 Admin Guide (page no. 273, 274, 423 & 425)

I would say - everything you want is there into documentation, you will need to read it.

Hope this helps you...