Tapes are taking too much time to expire

Hi,

Since past 3 days, we are facing an issue with the tape expiration.

In our environment, We expires 30 tapes daily with bpexpdate command. 

Previously we used to expire each tape within 5 minutes.

But now it is taking almost 40 minutes to expire each tape.

We haven't made any upgrades/activites in recent times. Suddenly since past 3 days, we are facing this issue.

Please help.

Details:

Netbackup version: 7.0.1

Master server OS:  SunOS 5.10

Media Server OS : AIX 6.1 (2 media servers)

Regards

Sai