freebsd-src/man/man8/vdev_id.8
Ned Bass 2957f38d78 vdev_id support for device link aliases
Add a vdev_id feature to map device names based on already defined
udev device links.  To increase the odds that vdev_id will run after
the rules it depends on, increase the vdev.rules rule number from 60
to 69.  With this change, vdev_id now provides functionality analogous
to zpool_id and zpool_layout, paving the way to retire those tools.

A defined alias takes precedence over a topology-derived name, but the
two naming methods can otherwise coexist. For example, one might name
drives in a JBOD with the sas_direct topology while naming an internal
L2ARC device with an alias.

For example, the following lines in vdev_id.conf will result in the
creation of links /dev/disk/by-vdev/{d1,d2}, each pointing to the same
target as the device link specified in the third field.

  #     by-vdev
  #     name     fully qualified or base name of device link
  alias d1       /dev/disk/by-id/wwn-0x5000c5002de3b9ca
  alias d2       wwn-0x5000c5002def789e

Also perform some minor vdev_id cleanup, such as removal of the unused
-s command line option.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #981
2012-12-03 14:04:47 -08:00

78 lines
2.4 KiB
Groff

.TH vdev_id 8
.SH NAME
vdev_id \- generate user-friendly names for JBOD disks
.SH SYNOPSIS
.LP
.nf
\fBvdev_id\fR <-d dev> [-c config_file] [-g sas_direct|sas_switch]
[-m] [-p phys_per_port]
\fBvdev_id\fR -h
.fi
.SH DESCRIPTION
The \fBvdev_id\fR command is a udev helper which parses the file
.BR /etc/zfs/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 re-mapped 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 and sas_switch. A
multipath mode is supported in which dm-mpath devices are handled by
examining the first-listed running component disk as reported by the
.BR multipath (8)
command. In multipath mode the configuration file should contain a
channel definition with the same name for each path to a given
enclosure.
.BR vdev_id
also supports creating aliases based on existing udev links in the /dev
hierarchy using the \fIalias\fR configuration file keyword. See the
.BR vdev_id.conf (5)
man page for details.
.SH OPTIONS
.TP
\fB\-c\fR <config_file>
Specifies the path to an alternate configuration file. The default is
/etc/zfs/vdev_id.conf.
.TP
\fB\-d\fR <device>
This is the only mandatory argument. Specifies the name of a device
in /dev, i.e. "sda".
.TP
\fB\-g\fR <sas_direct|sas_switch>
Identifies a physical topology that governs how physical paths are
mapped to channels.
\fIsas_direct\fR - in this mode a channel is uniquely identified by
a PCI slot and a HBA port number
\fIsas_switch\fR - in this mode a channel is uniquely identified by
a SAS switch port number
.TP
\fB\-m\fR
Specifies that
.BR vdev_id (8)
will handle only dm-multipath devices. If set to "yes" then
.BR vdev_id (8)
will examine the first running component disk of a dm-multipath
device as listed by the
.BR multipath (8)
command to determine the physical path.
.TP
\fB\-p\fR <phys_per_port>
Specifies the number of PHY devices associated with a SAS HBA port or SAS
switch port.
.BR vdev_id (8)
internally uses this value to determine which HBA or switch port a
device is connected to. The default is 4.
.TP
\fB\-h\fR
Print a usage summary.
.SH SEE ALSO
.LP
\fBvdev_id.conf\fR(5)