NetBackup bpbkar appears to hang in granular recovery technology processing during Exchange GRT Backups
For example, during an Exchange Granular Recovery Technology (GRT) backup, the Exchange Information Store is backed up first and then the backup image is mounted on the Exchange client or proxy client to start a jet database to process granular mailbox items. The disk transactions that the NetBackup nbfsd process performs during the GRT phase is similar to those of a database and NetBackup may perform many millions of operations while reading the data from the Exchange Information store database.
For best performance, Symantec recommends that the disk storage unit being used as a target for GRT backups be located locally on the media server as direct SCSI or SAN attached disks. The use of disk storage units that write to network based file systems (NFS or CIFS) is not recommended or supported by NetBackup at this time. Performance degradation or read errors may result when the media server presents the backup image via NFS to the client or proxy client if the NFS exported image itself is residing on a network file system (NFS or CIFS).