Hello,
It's suggested that you could go to the following link, and go through its relevant documents, e.g. release notes, admin guide, etc, and I believe you could get some useful info about this product.
http://www.symantec.com/business/support/index?page=content&id=DOC2792 (Links to the Symantec NetBackup 52xx Appliance Documentation)
In addition, you could refer to my last post in the following link,
https://www-secure.symantec.com/connect/forums/migrate-puredisk-data-msdp-clarification
Simply speaking, for pd appliance, it has two usages:
1. Used as PDDO, which is deduplication storage destination of NetBackup.
2. Used as PureDisk Server, which has its own storage pool, and used to protect remote offices with puredisk agent installed, standalone backup system similar to others, e.g. netbackup, BE.
for nbu appliance, it can use PDDO as storage unit, also can use MSDP or others as storage unit.
hope helps.
Thanks
