Notes on DEVFS serial number support

Matthew Dillon dillon at
Wed Aug 5 22:18:50 PDT 2009

    Note:  With these commits a full world & kernel build is required to
    get the new features.  Multi-volume HAMMER mounts specifying devtab
    labels won't work yet (I'm not sure how best to parse them), but
    they should work using serno/* paths.

    My recommendation here is that people not worry so much about mounting
    by serial number unless they have a bunch of drives.  Ultimately this
    will become a very powerful feature as networked drive support is added.
    For now its claim to fame is to remove issues with drive unit iterations
    when a drive is removed.

    Also note that vinum is not operational in master at the moment.


    DEVTAB - Add mountroot & fstab support for serial numbers, and devtab.
    * The vfs.root.mountfrom /boot/loader.conf variable may now specify
      devfs aliases, allowing it to specify root mounts by serial number.
      Here is an example:
      Note that vfs.root.mountfrom may NOT currently specify /etc/devtab labels.
    * /etc/fstab may now specify devfs relative paths (such as serial numbers)
      as well as /etc/devtab labels.  A ".suffix" may be used to extend the
      translation so /etc/devtab only needs to specify the base label.
      Example /etc/fstab:
        # Device                Mountpoint FStype  Options  Dump    Pass
        driveA.s1d              /          hammer  rw       1       1
        driveA.s1b              none       swap    sw       0       0
        driveA.s1a              /boot      ufs     rw       1       1
        serno/L41JYE0G.s1f      /fubar     hammer  rw       1       1
        driveA          serno   L41JYE0G

					Matthew Dillon 
					<dillon at>

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