Back up NFS file systems with the global namespace feature

NFS V4 clients can back up NFS file systems that are mounted by using the global namespace feature, which is called a referral. All file systems in the global namespace are backed up under a single file space.

The following examples show the file systems in the global namespace that are backed up under a single file space:

   server 'publications' has /doc file system
   server 'projects' has /projects file system
   server 'data'  has /data file system

The server account1 is the main NFS server that exports all these files systems by using a referral, and it is the server that all of the clients recognize. The /etc/exports directory on account1 looks like the following examples:

   /doc -vers=4,refer=/doc@publications 
   /projects -vers=4,refer=/projects@projects 
   /data -vers=4,refer=/data@data

The client payroll mounts directories from the account1 server and can access all three file systems:

   payroll:/#mount -o vers=4 account1:/ /mnt
   payroll:/#ls /mnt 
   doc/ projects/ data/

The client payroll can back up the /mnt file as one NFS file system, which backs up all other file systems.

Important: Using the virtualmountpoint option can improve system performance when you back up NFSV4 file systems by using the global namespace. Add the following entries in a stanza in dsm.sys to back up each mounted directory as a separate file space:

   VIRTUALMOUNTPOINT  /doc
   VIRTUALMOUNTPOINT  /projects
   VIRTUALMOUNTPOINT  /data