Backing up large network attached storage (NAS) data is typically a painful, clunky and unrealiable process.
Many backup using the Network Data Management Protocol (NDMP), a protocol that enables to transportation between NAS devices and backup devices.
The main advantage of NDMP is that it removes the need for transporting that data through the backup server itself and can directly offload to secondary storage.
However it does have quite a few pitfalls including the following:
- NDMP is not storage agnostic
In general you cannot backup data and restore to another array from another vendor or sometimes even another OS version. This means you need an identical array to recover onto so it is a very inflexible solution. - The majority of the backup software solutions do not index the files of the NDMP files
For example in Spectrum Protect you can store a Table of Content (TOC) with the backup but if you want to restore a single file you have to load the TOC into a temporary table to work with it. This is typically very time consuming. - NDMP doesn't really support a incremental forever strategy
That means it doesnt scale well and you have to do a full backup periodically which is a no go with large filesystems at petabyte scale that contain billions of files.
