nfs_autofs.txt

Mounting Network-Attached Storage with NFS

NFS(Network File System)
-an internet standard protocol used by Linux
-used as a native network file system (for Linux, UNIX,etc.) 
-supports native Linux permissions and file-system features

1.NFS servers export shares (directories). 
2.NFS clients mount an exported share to a local mount point (directory), 
  which must exist. 
3.NFS shares can be mounted a number of ways:
  - Manually, using the mount command.

  - Automatically at boot time using /etc/fstab entries.

  - On demand, using either the autofs service or the systemd.automount 
    facility. 

Mounting NFS Shares

Steps:

1.Identify
  Ex:
   a. sudo mkdir mountpoint
   b. sudo mount serverb:/ mountpoint
   c. sudo ls mountpoint

2.Create Mount Point
  Ex:
   - mkdir -p mountpoint

3.Mount NFS
  Ex1:Mount temporarily
   a. via mount cmd
      sudo mount -t nfs -o rw,sync serverb:/share mountpoint

**"-t" optionis the file system type
**"-o sync" option tells mount to immediately synchronize write operations 
  with the NFS server (the default is asynchronous)

Important!
The method above mounts the share immediately but NOT persistently

 OR...
  
  Ex2:Mount persistently
   a. via /etc/fstab config file
      sudo vim /etc/fstab
      (entry) - serverb:/share  /mountpoint  nfs  rw,soft  0 0

   b. then,
      sudo mount /mountpoint

**************

Unmmounting NFS Shares

1.sudo umount mountpoint


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Mounting NFS Shares with the Automounter(autofs)

automounter;
- is a service (autofs) that automatically mounts NFS shares "on-demand," and will automatically 
  unmount NFS shares when they are no longer being used

Creat an automount

Steps:

1.Install the autofs package.
  Ex:
   - sudo yum install autofs

2.Add a master map file to /etc/auto.master.d.
  Ex:
   - sudo vim /etc/auto.master.d/demo.autofs
   - entry --> /shares  /etc/auto.demo

**this file identifies the base directory used for mount points and identifies the mapping file used 
  for creating the automounts.

**must have an extension of .autofs for the subsystem to recognize it.**

3.Create the mapping files.
  Ex:
   - sudo vim /etc/auto.demo
   - entry --> work  -rw,sync  serverb:/shares/work

**the mapping file-naming convention is /etc/auto.name, where name reflects the content of the map.

**the format of an entry is mount point, mount options, and source location.

4.Start and enable the automounter service.
  Ex:
   - sudo systemctl enable --now autofs

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Direct Maps
 
- used to map an NFS share to an existing absolute path mount point
- direct map entries use "/-" as the base directory

The master map file might appear as follows:
Ex:
   /-  /etc/auto.direct

The content for the /etc/auto.direct file might appear as follows:
Ex:
  /mnt/docs  -rw,sync  serverb:/shares/docs

**The mount point (or key) is always an absolute path. 
  The rest of the mapping file uses the same structure.

Indirect Wildcard Maps

When an NFS server exports multiple subdirectories within a directory, then the automounter 
can be configured to access any one of those subdirectories using a single mapping entry.

Continuing the previous example, if serverb:/shares exports two or more subdirectories and they 
are accessible using the same mount options, then the content for the /etc/auto.demo file might 
appear as follows:

Ex:
   *  -rw,sync  serverb:/shares/&

**The mount point (or key) is an asterisk character (*), and the subdirectory on the source 
  location is an ampersand character (&). Everything else in the entry is the same.