vdev_id — generate
    user-friendly names for JBOD disks
  
    vdev_id | 
    -d dev
      -c config_file
      -g
      sas_direct|sas_switch|scsi
      -m -p
      phys_per_port | 
  
vdev_id is an udev helper which parses
    vdev_id.conf(5)
    to map a physical path in a storage topology to a channel name. The channel
    name is combined with a disk enclosure slot number to create an alias that
    reflects the physical location of the drive. This is particularly helpful
    when it comes to tasks like replacing failed drives. Slot numbers may also
    be remapped in case the default numbering is unsatisfactory. The drive
    aliases will be created as symbolic links in
    /dev/disk/by-vdev.
The currently supported topologies are
    sas_direct, sas_switch, and
    scsi. A multipath mode is supported in which dm-mpath
    devices are handled by examining the first running component disk as
    reported by the driver. In multipath mode the configuration file should
    contain a channel definition with the same name for each path to a given
    enclosure.
vdev_id also supports creating
    aliases based on existing udev links in the /dev hierarchy using the
    alias configuration
    file keyword. See
    vdev_id.conf(5)
    for details.
  -d
    device 
  - The device node to classify, like /dev/sda.
 
  -c
    config_file 
  - Specifies the path to an alternate configuration file. The default is
      /etc/zfs/vdev_id.conf.
 
  -g
    sas_direct|sas_switch|scsi 
  - Identifies a physical topology that governs how physical paths are mapped
      to channels:
    
      - sas_direct
        and scsi
 
      - channels are uniquely identified by a PCI slot and HBA port
        number
 
      - sas_switch
 
      - channels are uniquely identified by a SAS switch port number
 
    
   
  -m 
  - Only handle dm-multipath devices. If specified, examine the first running
      component disk of a dm-multipath device as provided by the driver to
      determine the physical path.
 
  -p
    phys_per_port 
  - Specifies the number of PHY devices associated with a SAS HBA port or SAS
      switch port. 
vdev_id internally uses this value to
      determine which HBA or switch port a device is connected to. The default
      is 4. 
  -h 
  - Print a usage summary.