Permissions on media

Within the job setup

In the job setup you let BE know that wheather you want to "append"  "overwrite" or "append, if no 

appenable media then overwrite". So as per the selection BE looks for the media in the media set 

which is linked with the job. If you select the job to overwrite and if no overwritable media is available in 

the media set then BE will look for an overwritable media in the scratch media set.

Within the media set assigned to a particular job

In the Media set you just specify how long you need to protect data and append data.

Within the Device configuration ( Actually its in Media Management)

In BE console, Tools->Options->Media Management-> Set the "Overwrite Protection Level"

If the level is set to "Full or Partial" then the above settings will come in picture. If "None" is selected

then Backup Exec will override all the rules and settings applied in the Job and  Media set.

Refer to http://www.symantec.com/docs/HOWTO22313

             http://www.symantec.com/docs/TECH5459

I see that permissions regarding overwriting or appending of media can be set in 3 different places:

Within the job setup

Within the media set assigned to a particular job

Within the Device configuration

Well, Kind of

In the job setup you specify whether the job will overwrite or append when it starts

The medai set specifies how long from initial allocation, that a media can be appended to (it is not reset by following jobs) or how long a media is protected from overwrite after the last data is written to it  (is reset at the end of each append job)

I'm not sure how you figure that Device Configuration has any bearing on OPP and/or APP at all

For example if i "set a job" to append to media yet within the media set it is set to "overwrite" which permission will take effect?

 The job specifies how BackupExec attempts to open each media, either for Overwrite or Append.  The media set that the media  belongs to and either it's allocation date or last update tume will determine whether the media can be used by that job

Used to be  a Tech Note that explained ADAMM (Advanced Device and Media Management) but I can't find it right now.  if I can, I'll edit this to add it

It is covered  in the Admin Guide tho, see page 451