[In part 1 of this 2 part series, I gave a brief overview of alternatives to NDMP.  In this post, I’m going to discuss in a bit more detail the advantages and disadvantages of each.]

Here’s a table of the advantages and disadvantages of alternatives to NDMP and NDMP itself.

Protection Method

Advantages

Disadvantages

Client-Based NAS Attach

  • Supports backup and subsequent restores to different NASs.
  • Supports concurrent backups for higher performance.
  • May use native CIFS or NFS.
  • Indirect protection; increases load on customer’s computer.
  •  Indirect protection; decreases performance.
  • With CIFS or NFS extended ownership and permission attributes may not be supported.
  • Does not offer Microsoft VSS-level open file protection.

Direct NAS Attach

  • Direct protection; no load on customer’s computer.
  • Direct protection; faster performance due to direct D2D copy.
  • Supports backup and subsequent restores to different NASs (no vendor-proprietary lock-in.)
  • Supports concurrent D2D backups for higher performance.
  • May use native CIFS or NFS.open file protection.
  • If used with byte-level (content aware) deduplication, will have better deduplication ratios.
  • If used with intelligent compression, will have better compression ratios.
  •  With CIFS or NFS extended ownership and permission attributes may not be supported.
  • Does not offer Microsoft VSS-level open file protection.

NDMP

  • Direct protection; no load on customer’s computer.
  • Direct protection; faster performance due to direct D2D or tape copy.
  • May use native NDMP; extended ownership and permission attributes may be supported.
  • Sometimes supports multiplexed streams for faster performance via concurrency [not available on many implementations.]
  • Not implemented on all NASs, particularly more affordable NASs.
  • Can be difficult to perform file-level restores given the underlying implementation of NDMP (which is typically just a batched “dump” command.)
  • Does not support backup and subsequent restores to different NASs (vendor proprietary- lock-in.)
  • Many versions do not support concurrent D2D backups for higher performance (originally designed for tape.)
  • Does not offer Microsoft VSS-level open file protection.

Since I originally wrote this in response to a customer asking me what Unitrends does, the answer is that we support direct NAS attach.  That way we support small NASs (such as the Drobo,  NetGear Readynas, Iomega, Qnap, and other smaller NAS devices), entry level unified storage such as the EMC VNX/VNXe and NetApp FAS2000 series, all the way up to scale-out NAS from vendors such as EMC, NetApp, Dell, Nexsan, and others.