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Mounting Network Filesystems

The three methods of mounting network filesystems (immediate mount -command line-; always mounted; and mounted on-demand) use a common configuration file /etc/fstab. Over the years, additional features and services have updated the options in /etc/fstab. Functionality that required external packages, services and configuration are now combined under systemd services.

The /etc/fstab has slightly changed its purpose with systemd from configuration file to drive the mount command during system initialization to an input configuration file for the systemd-fstab-generator that creates native unit files used by systemd.mount during system startup. The regular mount command still looks in the /etc/fstab file.

Since the preferred method to configure file system mounts is still /etc/fstab, nothing has changed for most mount options. See man systemd.mount for additional details.

mount Command​

The universal mounting command can mount many types of filesystems, including NFS and cifs filesystems.

  • If the device name is in the format SERVERNAME:/share, then NFS is assumed.
  • If the device name is in the format SERVERNAME//share, then cifs is assumed.
  • In most cases, the -t fstype is optional.
  • Supports options specific to the filesystem, like the cifs username and do- main options.

Persistent Mounting Network File Systems​

Network filesystems can be persistently mounted through /etc/fstab:

  • the fs_vfstype field must be set, usually to one of the following: nfs, cifs or nfs4
  • the fs_mntopts field can contain options specific the network filesystem
  • the fs_freq field is generally set to 0
  • the fs_passno is generally set to 0; setting this field to a non-zero value may cause a delay during system startup time waiting for the mount to complete.

Automount Network File Systems​

The automount will monitor a configured mount point and, if the information in the filesystem is accessed, the mount will be executed.

There may be an option to disconnect an idle connection.

  • autofs

    • Requires additional packages to be installed.
    • Multi-part configuration files.
    • May require scripts as helpers for mounting some filesystem.

  • systemd.automount

    • Integrated into systemd.
    • Only available on systemd distributions.
    • Unified configuration files, uses /etc/fstab.
    • Uses common systemd.mount facilities, no scripts, but allows unit file overrides.

With the systemd.automount implementation, the actual unit configuration files are generated from the entries in /etc/fstab. There are options to add to the /etc/fstab to indicate to the systemd-fstab-generator the entries are to be automounted. The systemd unit files that are generated are located in the /run/systemd/generator directory. The file names end in mount and automount. Like other systemd files, they can be overridden by entries in the /etc/systemd/system directory, but it is easier to just change the options in /etc/fstab. The man page for systemd.mount has information on the options. Some examples from /etc/fstab are provided below:

127.0.0.1:/home/export/nfs /home/share/nfs nfs x-systemd.automount,x-systemd.idle-timeout=10,noauto,_netdev 0 0 //localhost/cifs-share /home/share/cifs cifs creds=/root/smbfile,x-systemd.automount,x-systemd.idle-timeout=10,noauto,_netdev 0 0