Hi,
        Yesterday there was some discussion on these mailing
        lists regarding NDMP and limitations on restores, etc.
        
        We'd like to thank you for your feedback and to explain
        what the current focus of NDMP is and in particular
        how NetApp's chosen long term archivable backup format
        (dump) works within NDMP.

        Over the last few years NDMP has grown from
        essentially a 2 company (PDC then IntelliGuard now
        Legato and Network Appliance) backup solution to a
        community with 20+ companies participating and > 25
        NDMP compliant products shipping. The community
        has backup software companies, tape library vendors
        and file system vendors working together to achieve
        true interoperability and a growing set of features.
        This was the vision of the original companies.

        Recently, this has resulted in a new V4 specification
        that essentially is a cleanup of V2 & V3 and has
        added extensibility so that new features may be
        added without waiting for a spec change. V4
        implementations will arrive this year from multiple
        companies and should put an end to interoperability
        issues that have cropped up from time to time.

        NDMP (http://www.ndmp.org) is essentially a "plumbing"
        api for controlling data protection/management operations
        right now and has remained data format independant/neutral.
        This means that it is relatively easy for backup software
        companies to "plumb" a backup or restore that uses the
        native format(s) of each system vendor.

        There are 3 basic data formats commonly used in tape
        backups, cpio, tar & dump (should we include MicroSoft
        tape format?). Some operating systems such as Solaris
        currently support all three. However, some systems such
        as WAFL support one, i.e. BSD's dump. Even though systems
        vendors have these native commands, most backup software
        companies choose to write their own agents based on one
        of the 3 formats discussed and tend to add some
        "proprietaryness" as they support more and more dissimilar
        file systems or add performance optimizations such as
        multiplexing, etc.

        NetApp's dump is no stranger to this, we have added support
        for qtree metadata, NT ACLs, Unicode, NT Streams. However, a
        standard BSD restore compatible application such as Solaris'
        ufsrestore can still restore the data, but will only restore
        NFS attributes. So should you have zero filers in 10 years
        (heaven forbid) and a pile of NDMP/dump tapes to restore from
        then as long as you have access to a dump compatible restore
        program you should be able to manually retrieve your data.

        Legato's BudTool product proved that NetApp data could be
        restored on non-NetApp storage either in a disaster recovery
        scenario or because that is what the customer wants. We'd like
        to think that some if not all of the current 7 NDMP-compliant
        backup software applications that support NetApp could add the
        same capability.

        Marion asks for a standard backup tape format that can be
        interchanged between NDMP-compliant vendors and we applaud
        her for it. However, that is beyond the current scope of the
        NDMP community or the SNIA Backup working group in general.

        We think its going to take an awful lot of persuading to get
        all the current backup software vendors to define a single
        format and then have all the possible system vendors support
        it. Most companies have chosen their solution based on
        trying to differentiate themselves from all the others and
        we see that continuing for some time.

Cheers,
        Grant and Greg

Greg Linn
Manager, NDMP Development
linn AT netapp DOT com
408.822.3752 

=========== grant AT netapp DOT com  ========== Grant Melvin
===                                  === Software Development Manager 
===                                  === Data Availability & Management
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