Hi Nagendra, does this answer you question:
Catalog Snapshots For Backup
By default, data is cataloged during an IntelliSnap backup. Depending on many factors, such as the number of files on the file server volume, this operation can be time consuming. You can enhance the performance of this operation by delaying the cataloging phase of the backup to a later time. This feature enables you to reduce the load on the primary file server.
By default , cataloging is done on the primary copy but if you want to reduce the load on the server, use the mirror or vault copy.