freebsd-dev/sbin/vinum/vinum.8

.\"  Hey, Emacs, edit this file in -*- nroff-fill -*- mode
.\"
.Dd 11 July 1998
.Dt vinum 8
.Os FreeBSD
.Sh NAME
.Nm vinum
.Nd Logical Volume Manager control program
.Sh SYNOPSIS
.Nm
.Op command
.Op Fl options
.Sh COMMANDS
.Cd create
.Ar description-file
.in +1i
Create a volume as described in 
.Ar description-file
.in
.\" XXX remove this
.Cd attach Ar plex Ar volume 
.Op Nm rename
.Cd attach Ar subdisk Ar plex Ar [offset]
.Op Nm rename
.in +1i
Attach a plex to a volume, or a subdisk to a plex.
.in
.\" XXX remove this
.Cd debug
.in +1i
Cause the volume manager to enter the kernel debugger.
.in
.Cd detach
.Op Ar plex | subdisk
.in +1
Detach a plex or subdisk from the volume or plex to which it is attached.
.in
.Cd info
.Op Fl v
.in +1i
List information about volume manager state.
.in
.Cd init
.Op Fl v
.in +1i
.\" XXX
Initialize a plex by writing zeroes to all its subdisks.
.in
.Cd label
.Ar volume
.in +1i
Create a volume label
.in
.Cd list
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume | plex | subdisk
.in +1i
List information about specified objects
.in
.Cd l
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume | plex | subdisk
.in +1i
List information about specified objects (alternative to
.Cd list
command)
.in
.Cd ld
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume
.in +1i
List information about drives
.in
.Cd ls
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op subdisk
.in +1i
List information about subdisks
.in
.Cd lp
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op plex
.in +1i
List information about plexes
.in
.Cd lv
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume
.in +1i
List information about volumes
.in
.Cd makedev
.in +1i
Remake the device nodes in /dev/vinum.
.in
.Cd read
.Ar disk-partition
.in +1i
Read the
.Nm
configuration from the specified disk partition.
.in
.Cd rename Op Fl r
.Ar [ drive | subdisk | plex | volume ]
.Ar newname
.in +1i
Change the name of the specified object.
.in
.Cd replace
.Ar [ subdisk | plex ]
.Ar newobject
.in +1i
Replace the object with an identical other object.  XXX not implemented yet.
.in
.Cd resetconfig
.in +1i
Reset the complete
.Nm
configuration.
.in
.Cd resetstats
.Op Fl r
.Op volume | plex | subdisk
.in +1i
Reset statistisc counters for the specified objects, or for all objects if none
are specified.
.in
.Cd rm 
.Op Fl f
.Op Fl r
.Ar volume | plex | subdisk
.in +1i
Remove an object
.in
.ig
XXX
.Cd set
.Op Fl f
.Ar state
.Ar volume | plex | subdisk | disk
.in +1i
Set the state of the object to \fIstate\fP\|
.in
..
.Cd start
.Op volume | plex | subdisk
.in +1i
Allow the system to access the objects
.in
.Cd stop
.Op Fl f
.Op volume | plex | subdisk
.in +1i
Terminate access the objects
.in
.Sh DESCRIPTION
.Nm
is a utility program to communicate with the \fBVinum\fP\| logical volume
manager.  See
.Xr vinum 4
for more information about the volume manager.
.Xr vinum 8
is designed either for interactive use, when started without a command, or to
execute a single command if the command is supplied as arguments to
.Nm vinum.
.Ss OPTIONS
.Nm
commands may optionally be followed by an option.  Any of the following options
may be specified with any command, but in some cases they do not make any
difference: cases, the options are ignored.  For example, the
.Nm stop
command ignores the 
.Fl v
and
.Fl V
options.
.Bl -hang
.It Cd -v
The
.Nm -v
option can be used with any command to request more detailed information.  
.It Cd -V
The
.Nm -V
option can be used with any command to request more detailed information than
the
.Nm -v
option provides.
.It Cd -f
The
.Nm -f
option overrides safety checks.  Use with extreme care.  This option is for
emergency use only.  For example, the command
.Bd -unfilled -offset indent
rm -f myvolume
.Ed
.Pp
removes
.Nm myvolume
even if it is open.  Any subsequent access to the volume will almost certainly
cause a panic.
.It Cd -r
The
.Nm -r
(``recursive'') option is used by the list commands to display information not
only about the specified objects, but also about subordinate objects.  For
example, in conjnction with the
.Nm lv
command, the
.Nm -r
option will also show information about the plexes and subdisks belonging to the
volume.
.It Cd -s
The
.Nm -s
option is used by the list commands to display statistical information.
.El
.Pp
.Ss COMMANDS IN DETAIL
.Pp
.Nm
commands perform the following functions:
.Bl -hang
.It Nm attach Ar plex Ar volume
.Op Nm rename
.sp -1v
.It Nm attach Ar subdisk Ar plex Ar [offset]
.Op Nm rename
.sp
.Nm
.Ar attach
inserts the specified plex or subdisk in a volume or plex.  In the case of a
subdisk, an offset in the plex may be specified.  If it is not, the subdisk will
be attached at the first possible location.  After attaching a plex to a
non-empty volume,
.Nm
reintegrates the plex.
.Pp
If the keyword
.Nm rename
is specified,
.Nm
renames the object (and in the case of a plex, any subordinate subdisks) to fit
in with the default
.Nm 
naming convention.
.Pp
A number of considerations apply to attaching subdisks:
.Bl -bullet
.It
Subdisks can normally only be attached to concatenated plexes.
.It
If a striped or RAID-5 plex is missing a subdisk (for example after drive
failure), it may be replaced by a subdisk of the same size only.  No other
attachment of subdisks is currently allowed.
.It
For concatenated plexes, the
.Ar offset
parameter specifies the offset in blocks from the beginning of the plex.  For
striped and RAID-5 plexes, it specifies the offset of the first block of the
subdisk: in other words, the offset is the numerical position of the subdisk
multiplied by the stripe size.  For example, in a plex of block size 256k, the
first subdisk will have offset 0, the second offset 256k, the third 512k, etc.
This calculation ignores parity blocks in RAID-5 plexes.
.El
.It Nm create Ar description-file
.sp
.Nm
.Ar create
is used to create any object.  In view of the relatively complicated
relationship and the potential dangers involved in creating a
.Nm
object, there is no interactive interface to this function.  See the section
CONFIGURATION FILE below for more information.
.It Nm debug
.Pp
.Nm
.Ar debug
is used to enter the remote kernel debugger.  It is only activated if
.Nm
is built with the DEBUG option.  This option will stop the execution of the
operating system until the kernel debugger is exited.  If there is no remote
connection for a kernel debugger, it will be necessary to reset the system and
reboot in order to leave the debugger.
.It Nm detach Op Fl f 
.Ar plex
.sp -1v
.It Nm detach Op Fl f 
.Ar subdisk
.sp
.Nm
.Ar detach
removes the specified plex or subdisk from the volume or plex to which it is
attached.  If removing the object would impair the data integrity of the volume,
the operation will fail unless the
.Fl f
option is specified.  If the object is named after the object above it (for
example, subdisk vol1.p7.s0 attached to plex vol1.p7), the name will be changed
by prepending the text ``ex-'' (for example, ex-vol1.p7.s0).  If necessary, the
name will be truncated in the process.
.Pp
.Nm detach
does not reduce the number of subdisks in a striped or RAID-5 plex.  Instead,
the subdisk is marked absent, and can later be replaced with the
.Nm attach
command.
.It Nm info
.Pp
.Nm
.Ar info
displays information about
.Nm
memory usage.  This is intended primarily for debugging.  With the 
.Fl v
option, it will give detailed information about the memory areas in use.
.\" XXX
.It Nm init Ar plex
.Pp
.Nm
.Ar init
initializes a plex by writing zeroes to all its subdisks.  This is the only way
to ensure consistent data in a plex.  You must perform this initialization
before using a RAID-5 plex.  It is also recommended for other new plexes.
.Pp
.Nm 
initializes all subdisks of a plex in parallel.  Since this operation can take a
long time, it is performed in the background.  
.Nm
prints a console message when the initialization is complete.
.It Nm label
.Ar volume
.Pp
The
.Nm label
command writes a
.Ar ufs
style volume label on a volume.  It is a simple alternative to an appropriate
call to
.Ar disklabel . 
This is needed because some
.Ar ufs
commands still read the disk to find the label instead of using the correct
.Ar ioctl
call to access it.
.Nm
maintains a volume label separately from the volume data, so this command is not
needed for
.Ar newfs .
This command is deprecated.
.Pp
.It Nm list
.Op Fl r
.Op Fl V
.Op volume | plex | subdisk
.sp -1
.It Nm l
.Op Fl r
.Op Fl V
.Op volume | plex | subdisk
.sp -1
.It Nm ld
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume
.sp -1
.It Nm ls
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op subdisk
.sp -1
.It Nm lp
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op plex
.sp -1
.It Nm lv
.Op Fl r
.Op Fl s
.Op Fl v
.Op Fl V
.Op volume
.Pp
.Ar list
is used to show information about the specified object.  If the argument is
omitted, information is shown about all objects known to
.Nm vinum .
The
.Ar l
command is a synonym for
.Ar list .
.Pp
The
.Fl r
option relates to volumes and plexes: if specified, it recursively lists
information for the subdisks and (for a volume) plexes subordinate to the
objects.  The commands
.Ar lv ,
.Ar lp ,
.Ar ls 
and 
.Ar ld
commands list only volumes, plexes, subdisks and drives respectively.  This is
particularly useful when used without parameters.
.Pp
The
.Fl s
option causes
.Nm
to output device statistics, the
.Op Fl v
(verbose) option causes some additional information to be output, and the
.Op Fl V
causes considerable additional information to be output.
.It Nm makedev
.br
The
.Nm makedev
command removes the directory /dev/vinum and recreates it with device nodes
which reflect the current configuration.  This command is not intended for
general use, and is provided for emergency use only.
.Pp
.It Nm read
.Ar disk-partition
.Pp
The
.Nm read
command reads a previously created
.Nm
configuration from the specified disk partition.
.Nm
maintains an up-to-date copy of all configuration information on each disk
partition.  You can specify any of the partitions in a configuration as the
parameter to this command.
.It Nm rename
.Op Fl r
.Ar [ drive | subdisk | plex | volume ]
.Ar newname
.Pp
Change the name of the specified object.  If the
.Fl r
option is specified, subordinate objects will be named by the default rules:
plex names will be formed by appending .p\f(BInumber\fP to the volume name, and
subdisk names will be formed by appending .s\f(BInumber\fP to the plex name.
.It Nm replace
.Ar [ subdisk | plex ]
.Ar newobject
.Pp
Replace the object with an identical other object.  This command has not yet
been implemented.
.It Nm resetconfig
.Pp
The
.Nm resetconfig
command completely obliterates the
.Nm
configuration on a system.  Use this command only when you want to completely
delete the configuration.
.Nm
will ask for confirmation: you must type in the words NO FUTURE exactly
as shown:
.Bd -unfilled -offset indent
# \f(CBvinum resetconfig\f(CW

WARNING!  This command will completely wipe out your vinum
configuration.  All data will be lost.  If you really want
to do this, enter the text

NO FUTURE
Enter text -> \f(BINO FUTURE\fP
Vinum configuration obliterated
.Ed
.ft R
.It Nm resetstats
.Op Fl r
.Op volume | plex | subdisk
.Pp
.Nm
maintains a number of statistical counters for each object.  See the header file
.Fi vinumvar.h
for more information.
.\" XXX put it in here when it's finalized
Use the 
.Nm resetstats
command to reset these counters.  In conjunction with the
.Fl r
option, 
.Nm
also resets the counters of subordinate objects.
.It Nm rm 
.Op Fl f
.Op Fl r
.Ar volume | plex | subdisk
.Pp
.Nm rm
removes an object from the
.Nm
configuration.  Once an object has been removed, there is no way to recover it.
Normally
.Nm
performs a large amount of consistency checking before removing an object.  The
.Fl f
option tells
.Nm
to omit this checking and remove the object anyway.  Use this option with great
care: it can result in total loss of data on a volume.
.Pp
Normally,
.Nm
refuses to remove a volume or plex if it has subordinate plexes or subdisks
respectively.  You can tell
.Nm
to remove the object anyway by using the
.Fl f
flag, or you can cause
.Nm
to remove the subordinate objects as well by using the
.Fl r
(recursive) flag.  If you remove a volume with the
.Fl r
flag, it will remove both the plexes and the subdisks which belong to the
plexes.
.ig
.It Nm set
.Op Fl f
.Ar state
.Ar volume | plex | subdisk | disk
.Nm set
sets the state of the specified object to one of the valid states (see OBJECT
STATES below).  Normally
.Nm
performs a large amount of consistency checking before making the change.  The
.Fl f
option tells
.Nm
to omit this checking and perform the change anyway.  Use this option with great
care: it can result in total loss of data on a volume.
.\"XXX
.Nm This command has not yet been implemented.
..
.It Nm start
.Op volume | plex | subdisk
.Pp
.Nm start
starts the
.Nm
subsystem or one of its components.  To start a plex in a multi-plex volume, the
data must be copied from another plex in the volume.  This frequently takes a
long time and is done in the background.
.ig
XXX When invoked without arguments, it checks all disks connected to the system
for BSD partitions (type 165) and scans the partitions for a
.Nm
partition, which it calls a \fIdrive\fR\|.  The
.Nm
drive contains a header with all information about the data stored on the drive,
including the names of the other drives which are required in order to represent
plexes and volumes.
.\" XXX 
.Nm The scan function has not yet been implemented.
..
.It Nm stop
.Op Fl f
.Op volume | plex | subdisk
.Pp
.Nm stop
disables access to the specified objects and any subordinate objects.  It does
not remove the objects from the configuration.  They can be accessed again after
a
.Nm start 
command.
.Pp
By default, 
.Nm
does not remove active objects.  For example, you cannot remove a plex which is
attached to an active volume, and you cannot remove a volume which is open.  The
.Fl f
option tells
.Nm
to omit this checking and remove the object anyway.  Use this option with great
care and understanding: used incorrectly, it can result in serious data
corruption.
.El
.Ss CONFIGURATION FILE
.Nm
requires that all parameters to the
.Nm create
commands must be in a configuration file.  Entries in the configuration file
define volumes, plexes and subdisks, and may be in free format, except that each
entry must be on a single line.
.Pp
Some configuration file parameters specify a size (lengths, stripe sizes).
These lengths can be specified as bytes, as sectors of 512 bytes (by appending
the letter \f(CWb\fR), as kilobytes (by appending the letter \f(CWk\fR), as
megabytes (by appending the letter \f(CWm\fR) or as gigabytes (by appending the
letter \f(CWg\fR).  These quantities represent the values 2**10, 2**20 and 2**30
respectively.  For example, the value \f(CW16777216\fR bytes can also be written
as \f(CW16m\fR, \f(CW16384k\fR or \f(CW32768b\fR.
.Pp
The configuration file can contain the following entries:
.Pp
.Bl -hang
.It Nm volume
.Ar name 
.Op options
.Pp
Define a volume with name
.Ar name .
.Pp
Options are:
.Pp
.TS H
tab(#) ;
l lw50 .
Option#Meaning
.TH N
T{
.Nm plex
.Ar plexname
T}#T{
Add the specified plex to the volume.  If
.Ar plexname
is specified as 
.Ar * ,
.Nm
will look for the definition of the plex as the next possible entry in the
configuration file after the definition of the volume.
T}
.sp
T{
.Nm readpol
.Ar policy
T}#T{
Define a
.Ar read policy
for the volume.
.Ar policy
may be either 
.Nm round
or
.Nm prefer Ar plexname .
.Nm
satisfies a read request from only one of the plexes.  A
.Ar round
read policy specifies that each read should be performed from a different plex
in \fIround-robin\fR\| fashion.  A
.Ar prefer
read policy reads from the specified plex every time.
T}
.sp
T{
.Nm setupstate
T}#T{
When creating a multi-plex volume, assume that the contents of all the plexes
are consistent.  This is normally not the case, and correctly you should use the
.Nm init
command to first bring them to a consistent state.  In the case of striped and
concatenated plexes, however, it does not normally cause problems to leave them
inconsistent: when using a volume for a file system or a swap partition, the
previous contents of the disks are not of interest, so they may be ignored.
If you want to take this risk, use this keyword.  It will only apply to the
plexes defined immediately after the volume in the configuration file.  If you
add plexes to a volume at a later time, you must integrate them.
.Pp
Note that you \fImust\fP\| use the
.Nm init
command with RAID-5 plexes: otherwise extreme data corruption will result if one
subdisk fails.
T}
.fi
.TE
.It Nm plex
.Op options
.Pp
Define a plex.  Unlike a volume, a plex does not need a name.
.Pp
.TS H
tab(#) ;
l lw50 .
Option#Meaning
.TH N
T{
.Nm name
.Ar plexname
T}#T{
Specify the name of the plex.  Note that you must use the keyword
.Ar name
when naming a plex or subdisk.
T}
.sp
T{
.Nm org
.Ar organization
.Op stripesize
T}#T{
Specify the organization of the plex.
.Ar organization
can be one of 
.Ar concat ,
.Ar striped
or
.Ar raid5 .
For
.Ar striped
and
.Ar raid5 
plexes, the parameter
.Ar stripesize
must be specified, while for
.Ar concat
it must be omitted.  For type
.Ar striped ,
it specifies the width of each stripe.  For type
.Ar raid5 ,
it specifies the size of a group.  A group is a portion of a plex which
stores the parity bits all in the same subdisk.   It must be a factor of the plex size (in
other words, the result of dividing the plex size by the stripe size must be an
integer), and it must be a multiple of a disk sector (512 bytes).
.sp
For optimum performance, stripes should be at least 128 kB in size: anything
smaller will result in a significant increase in I/O activity due to mapping of
individual requests over multiple disks.  The increase in concurrency due to
this mapping will not make up for the increase in latency.  A good guideline for
stripe size is between 256 kB and 512 kB.
T}
.Pp
#T{
A striped plex must have at least two subdisks (otherwise it is a concatenated
plex), and each must be the same size.  A RAID-5 plex must have at least three
subdisks, and each must be the same size.  In practice, a RAID-5 plex should
have at least 5 subdisks.
T}
.Pp
T{
.Nm volume
.Ar volname
T}#T{
Add the plex to the specified volume.  If no
.Nm volume
keyword is specified, the plex will be added to the last volume mentioned in the
configuration file.
T}
.sp
T{
.Nm sd
.Ar sdname
.Ar offset
T}#T{
Add the specified subdisk to the  plex at offset
.Ar offset .
T}
.br
.fi
.TE
.It Nm subdisk
.Op options
.Pp
Define a subdisk. 
.Pp
.TS H
tab(#) ;
l lw50 .
Option#Meaning
.nf
.sp
T{
.Nm name
.Ar name
T}#T{
Specify the name of a subdisk.  It is not necessary to specify a name for a
subdisk\(emsee OBJECT NAMING above.  Note that you must specify the keyword
.Ar name
if you wish to name a subdisk.
T}
.sp
T{
.Nm plexoffset
.Ar offset
T}#T{
Specify the starting offset of the subdisk in the plex.  If not specified,
.Nm
allocates the space immediately after the previous subdisk, if any, or otherwise
at the beginning of the plex.
T}
.sp
T{
.Nm driveoffset
.Ar offset
T}#T{
Specify the starting offset of the subdisk in the drive.  If not specified,
.Nm
allocates the first contiguous
.Ar length
bytes of free space on the drive.
T}
.sp
T{
.Nm length
.Ar length
T}#T{
Specify the length of the subdisk.  This keyword must be specified.  There is no
default.
.Nm length
may be shortened to 
.Nm len .
T}
.sp
T{
.Nm plex
.Ar plex
T}#T{
Specify the plex to which the subdisk belongs.  By default, the subdisk belongs
to the last plex specified.
T}
.sp
T{
.Nm drive
.Ar drive
T}#T{
Specify the drive on which the subdisk resides.  By default, the subdisk resides
on the last drive specified.
T}
.br
.fi
.TE
.El
.Bl -hang
.It Nm drive
.Ar name
.Op options
.Pp
Define a drive.
.Pp
.TS H
tab(#) ;
l lw50 .
Option#Meaning
.nf
.sp
T{
.Nm device
.Ar devicename
T}#T{
Specify the device on which the drive resides.
T}
.TE
.El
.Sh EXAMPLE CONFIGURATION FILE
.nf
# Sample vinum configuration file
#
# Our drives
drive drive1 device /dev/da1h
drive drive2 device /dev/da2h
drive drive3 device /dev/da3h
drive drive4 device /dev/da4h
drive drive5 device /dev/da5h
drive drive6 device /dev/da6h
# A volume with one striped plex
volume tinyvol
 plex org striped 32b
  sd length 64m drive drive2
  sd length 64m drive drive4
volume stripe
 plex org striped 32b
  sd length 512m drive drive2
  sd length 512m drive drive4
# Two plexes
volume concat
 plex org concat
  sd length 100m drive drive2
  sd length 50m drive drive4
 plex org concat
  sd length 150m drive drive4
# A volume with one striped plex and one concatenated plex
volume strcon
 plex org striped 32b
  sd length 100m drive drive2
  sd length 100m drive drive4
 plex org concat
  sd length 150m drive drive2
  sd length 50m drive drive4
# a volume with a  RAID-5 and a striped plex
# note that the RAID-5 volume is longer by
# the length of one subdisk
volume vol5
 plex org striped 64k
  sd length 1000m drive drive2
  sd length 1000m drive drive4
 plex org raid5 32k
  sd length 500m drive drive1
  sd length 500m drive drive2
  sd length 500m drive drive3
  sd length 500m drive drive4
  sd length 500m drive drive5
.fi
.Ss DRIVE LAYOUT CONSIDERATIONS
.Nm
drives are currently BSD disk partitions.  They must be of type
.Ar unused 
in order to avoid overwriting file systems.  In later versions of
.Nm
this requirement will change to type
.Ar vinum .
Use
.Nm disklabel
.Ar -e
to edit a partition type definition.  The following display shows a typical
partition layout as shown by
.Nm disklabel:
.nf
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:    81920   344064    4.2BSD        0     0     0   # (Cyl.  240*- 297*)
  b:   262144    81920      swap                        # (Cyl.   57*- 240*)
  c:  4226725        0    unused        0     0         # (Cyl.    0 - 2955*)
  e:    81920        0    4.2BSD        0     0     0   # (Cyl.    0 - 57*)
  f:  1900000   425984    4.2BSD        0     0     0   # (Cyl.  297*- 1626*)
  g:  1900741  2325984    unused        0     0     0   # (Cyl. 1626*- 2955*)
.fi
.sp
In this example, partition 
.Nm g
may be used as a
.Nm
partition.  Partitions 
.Nm a ,
.Nm e 
and
.Nm f
may be used as
.Nm UFS
file systems or
.Nm ccd
partitions.  Partition 
.Nm b
is a swap partition, and partition
.Nm c
represents the whole disk and should not be used for any other purpose.
.Pp
.Nm
uses the first 265 sectors on each partition for configuration information, so
the maximum size of a subdisk is 265 sectors smaller than the drive.
.Sh GOTCHAS
.Nm
will not create a device on UFS partitions.  Instead, it will return an error
message ``wrong partition type''.  The partition type must currently be
``unused''.  See above for more details.
.Sh BUGS
.Nm
is currently in beta test.  Many bugs can be expected.  The configuration
mechanism is not yet fully functional.  If you have difficulties, please look at
http://www.lemis.com/vinum_beta.html and
http://www.lemis.com/vinum_debugging.html before reporting problems.
.Sh FILES
.Ar /dev/vinum
- directory with device nodes for
.Nm
objects.
.br
.Ar /dev/vinum/control
- control device for
.Nm vinum 
.br
.Ar /dev/vinum/plex
- directory containing device nodes for
.Nm
plexes.
.br
.Ar /dev/vinum/sd
- directory containing device nodes for
.Nm
subdisks.
.Sh SEE ALSO
.Xr vinum 4 
.Xr disklabel 8
.Sh AUTHOR
Greg Lehey 
.Pa <grog@lemis.com> .
.Sh HISTORY
The
.Nm
command first appeared in FreeBSD 3.0.