Backing Up Using NFS/CIFS without NDMP

Using NFS or CIFS to mount NAS volumes on a File Daemon machine allows to back up NAS files without the NDMP Plugin the same way it would be done with a local filesystem backup. However, when dealing with millions of small files, directory walking and network latency tend to decrease the backup throughput dramatically. By using techniques such as “Incremental forever” and Virtual Full backups that save only new and modified files, you can, however, achieve reasonable storage space consumption in this situation.

The Virtual Full feature reads the latest Full backup and all the Incrementals and merges them to create a new Full backup that looks like a “real” Full backup, but without having to access the NAS device. This kind of backup is sometimes referred to as a synthetic Full. During a Virtual Full backup, the data will be copied directly from one Bacula Volume to another, without accessing the NAS. See Virtual Full Jobs for more information on this subject.

Most NAS systems provide file system snapshot capabilities, and some of them also provide capabilities to avoid the file system walk to find modified or new files, which is a function typically built on top of the snapshot comparison. If those features are accessible, it is possible to perform a file level backups with both better consistency and less overhead using “Incremental Accelerator”. Bacula Systems offers such functionality for NetApp NAS systems and the nutanix_hfc plugins.

Using the NFS or CIFS protocols to do a complete restore of a large NAS file system can be excessively time consuming especially in urgent disaster recovery situations.

In addition, Access Control Lists (ACLs) are not always handled correctly using NFS/CIFS. Unix POSIX ACLs can be handled directly by Bacula, but backing up Windows ACLs needs special techniques (see the Saving Access Control Lists (ACLs) chapter).