we are also facing the same issue and it is resolved by doing this changes .

1. Reduced number of content revision from 30 to 20 (effect will reflect after 1-2 hrs).
2. Reduced number of days to store logs and file size.
3. Deleted old client install packages from SEPM.
 

These are the folders where Virus definitions are stored.

in the sepm under liveupdate you need to select what type of virus defs you want to download and product updates and for how long you want to keep them, the more you set and select the Higher will be the size.

if you think the size is quite high the definitions might be corrupted, You can clear those by following this document

http://www.symantec.com/connect/articles/how-clear...

"Thumbs up" to the advice, above!

The more content revisions that are kept on the SEPM, the better the SEPM will be at providing small delta updates to its clients (saving a lot of network bandwidth).  The trade-off is that the more content revisions are kept, the more hard drive space is consumed.

If hard drive space is growing short on the SEPM, reduce the number of content revisons kept. 

Also, make sure you are using the very latest release of SEP.

Hope this helps!

HI,

Check this artical

Symantec Endpoint Protection Manager installation folder is taking a lot of space

http://www.symantec.com/business/support/index?page=content&id=TECH165320

how many content revisions are retained?