freebsd/share/man/man4/vinum.4

.\"  Hey, Emacs, edit this file in -*- nroff-fill -*- mode
.\"	$NetBSD: ccd.4,v 1.5 1995/10/09 06:09:09 thorpej Exp $
.\"-
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.\" $Id: vinum.4,v 1.7 1998/11/05 01:28:56 grog Exp grog $
.\"
.Dd 22 July 1998
.Dt vinum 4
.Os FreeBSD
.Sh NAME
.Nm vinum
.Nd Logical Volume Manager
.Sh SYNOPSIS
.Cd "modload /lkm/vinum_mod.o"
.Cd "modload /lkm/Vinum_mod.o"
.Sh DESCRIPTION
.Nm
is a logical volume manager inspired by, but not derived from, the Veritas
Volume Manager.  It provides the following features:
.Bl -bullet
.It
It provides device-independent logical disks, called \fIvolumes\fP.  Volumes are
not restricted to the size of any disk on the system.
.It
The volumes consist of one or more \fIplexes\fP, each of which contain the
entire address space of a volume.  This represents an implementation of RAID-1
(mirroring).  Multiple plexes can also be used for
.\" XXX What about sparse plexes?  Do we want them?
.if t .sp
.Bl -bullet
.It
Increased read throughput.
.Nm
will read data from the least active disk, so if a volume has plexes on multiple
disks, more data can be read in parallel.
.Nm
reads data from only one plex, but it writes data to all plexes.
.It
Increased reliability.  By storing plexes on different disks, data will remain
available even if one of the plexes becomes unavailable.  In comparison with a
RAID-5 plex (see below), using multiple plexes requires more storage space, but
gives better performance, particularly in the case of a drive failure.
.It
Additional plexes can be used for on-line data reorganization.  By attaching an
additional plex and subsequently detaching one of the older plexes, data can be
moved on-line without compromising access.
.It
An additional plex can be used to obtain a consistent dump of a file system.  By
attaching an additional plex and detaching at a specific time, the detached plex
becomes an accurate snapshot of the file system at the time of detachment.
.\" Make sure to flush!
.El
.It
Each plex consists of one or more logical disk slices, called \fIsubdisks\fP.
Subdisks are defined as a contiguous block of physical disk storage.  A plex may
consist of any reasonable number of subdisks (in other words, the real limit is
not the number, but other factors, such as memory and performance, associated
with maintaining a large number of subdisks).
.It
A number of mappings between subdisks and plexes are available:
.Bl -bullet
.It
\fIConcatenated plexes\fP\| consist of one or more subdisks, each of which
is mapped to a contiguous part of the plex address space.
.It
\fIStriped plexes\fP\| consist of two or more subdisks of equal size.  The file
address space is mapped in \fIstripes\fP, integral fractions of the subdisk
size.  Consecutive plex address space is mapped to stripes in each subdisk in
.if n turn.
.if t \{\
turn:
.PS
move right 2i
down
SD0: box
SD1: box
SD2: box

"plex 0" at SD0.n+(0,.2)
"subdisk 0" rjust at SD0.w-(.2,0)
"subdisk 1" rjust at SD1.w-(.2,0)
"subdisk 2" rjust at SD2.w-(.2,0)
.PE
.\}
The subdisks of a striped plex must all be the same size.
.It
\fIRAID-5 plexes\fP\| require at least three equal-sized subdisks.  They
resemble striped plexes, except that in each stripe, one subdisk stores parity
information.  This subdisk changes in each stripe: in the first stripe, it is the
first subdisk, in the second it is the second subdisk, etc.  In the event of a
single disk failure,
.Nm
will recover the data based on the information stored on the remaining subdisks.
This mapping is particularly suited to read-intensive access.  The subdisks of a
RAID-5 plex must all be the same size.
.\" Make sure to flush!
.El
.It
.Nm Drives
are the lowest level of the storage hierarchy.  They represent disk special
devices.
.It
.Nm
offers automatic startup.  Unlike UNIX file systems,
.Nm
volumes contain all the configuration information needed to ensure that they are
started correctly when the subsystem is enabled.  This is also a significant
advantage over the Veritas\(tm File System.  This feature regards the presence
of the volumes.  It does not mean that the volumes will be mounted
automatically, since the standard startup procedures with
.Pa /etc/fstab 
perform this function.
.El
.Sh KERNEL CONFIGURATION
.Nm
does not require kernel configuration, since it is supplied \fIonly\fP\| as a
loadable kernel module (\fILKM\fP\|).  As with other LKMs, it is absolutely
necessary to match the LKM to the version of the operating system.  Failure to
do so will cause
.Nm
to issue an error message and terminate.
.Pp
.Nm
is currently available in two versions: a freely available version which does
not contain RAID-5 functionality, and a full version including RAID-5
functionality, which is available from Cybernet Systems
Inc. (http://www.cybernet.com\fR).
.Sh RUNNING VINUM
The freely available version of the
.Nm
LKM is called 
.Pa /lkm/vinum_mod.o ,
and the RAID-5 version is
.Pa /lkm/Vinum_mod.o .
To load the module:
.Bd -unfilled -offset indent
# modload /lkm/vinum_mod.o
.Ed
.Pp
At this point, 
.Nm
is loaded but has not been configured.  In an existing installation, the
following command reads the configuration from disk
.Ar /dev/da1h .
.Bd -unfilled -offset indent
# vinum read /dev/da1h
.Ed
.sp
The name of the disk device (in this example
.Ar /dev/da1h )
can be any of the devices used by
.Nm vinum .
These commands are normally embedded in the startup file
.Pa /etc/rc .
.Pp
See
.Xr vinum 8
for information on how to create a
.Nm
configuration.
.Pp
To unload the LKM, first find the
.Ar Id
field in 
.Pa modstat:
.Bd -unfilled -offset indent
# modstat
Type     Id Off Loadaddr Size Info     Rev Module Name
MISC      0   0 f2b6e000 0061 f2b7b034   1 vinum_mod
.Ed
.Pp
Use this value as the parameter for
.Pa modunload:
.Bd -unfilled -offset indent
# modunload -i 0
.Ed
.Pp
The LKM can only be unloaded when idle, in other words when no volumes are
mounted and no other instances of the
.Nm
program are active.  Unloading the LKM does not harm the data in the volumes.
.Ss CONFIGURING AND STARTING OBJECTS
Use the
.Xr vinum 8
utility to configure and start
.Nm 
objects.
.Sh IOCTL CALLS
.Pa ioctl
calls are intended for the use of the
.Nm
configuration program only.  The are described in the header file
.Pa /sys/sys/vinumio.h
.Ss DISK LABELS
Conventional disk special devices have a
.Em disk label
in the second sector of the device.  See
.Xr disklabel 5
for more details.  This disk label describes the layout of the partitions within
the device.
.Nm
does not subdivide volumes, so volumes do not contain a physical disk label.
For convenience,
.Nm
implements the ioctl calls DIOCGDINFO (get disk label), DIOCGPART (get partition
information), DIOCWDINFO (write partition information) and DIOCSDINFO (set
partition information).  DIOCGDINFO and DIOCGPART refer to an internal
representation of the disk label which is not present on the volume.  As a
result, the
.Fl r
option of
.Xr disklabel 8 ,
which reads the ``raw disk'', will fail.
.Pp
In general, 
.Xr disklabel 8
serves no useful purpose on a vinum volume.  If you run it, it will show you
three partitions, a, b and c, all the same except for the fstype, for example:
.Bd -unfilled -offset
3 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:     2048        0    4.2BSD     1024  8192     0   # (Cyl.    0 - 0)
  b:     2048        0      swap                        # (Cyl.    0 - 0)
  c:     2048        0    unused        0     0         # (Cyl.    0 - 0)
.Ed
.Pp
.Nm
ignores the DIOCWDINFO and DIOCSDINFO ioctls, since there is nothing to change.
As a result, any attempt to modify the disk label will be silently ignored.
.Sh MAKING FILE SYSTEMS
Since
.Nm
volumes do not contain partitions, the names do not need to conform to the
standard rules for naming disk partitions.  For a physical disk partition, the
last letter of the device name specifies the partition identifier (a to h).
.Nm
volumes need not conform to this convention, but if they do not,
.Nm newfs
will complain that it cannot determine the partition.  To solve this problem,
use the
.Fl v
flag to
.Nm newfs .
.Sh OBJECT NAMING
.Nm
assigns default names to plexes and subdisks, although they may be overridden.
We do not recommend overriding the default names.  Experience with the
.if t Veritas\(tm
.if n Veritas(tm)
volume manager, which allows arbitary naming of objects, has shown that this
flexibility does not bring a significant advantage, and it can cause confusion.
.sp
Names may contain any non-blank character, but it is recommended to restrict
them to letters, digits and the underscore characters.  The names of volumes,
plexes and subdisks may be up to 64 characters long, and the names of drives may
up to 32 characters long.  When choosing volume and plex names, bear in mind
that automatically generated plex and subvolume names are longer than the
name from which they are derived.
.Bl -bullet 
.It
When
.Nm vinum(8)
creates or deletes objects, it creates a directory
.Ar /dev/vinum ,
in which it makes device entries for each volume it finds.  It also creates 
subdirectories,
.Ar /dev/vinum/plex
and 
.Ar /dev/vinum/sd ,
in which it stores device entries for the plexes and subdisks.  In addition, it
creates two more directories,
.Ar /dev/vinum/vol
and
.Ar /dev/vinum/drive ,
in which it stores hierarchical information for volumes and drives.
.It
Unlike 
.Nm UNIX
drives,
.Nm
volumes are not subdivided into partitions, and thus do not contain a disk
label.  Unfortunately, this confuses a number of utilities, notably
.Nm newfs ,
which normally tries to interpret the last letter of a
.Nm
volume name as a partition identifier.  If you use a volume name which does not
end in the letters
.Ar a
to
.Ar c ,
you must use the
.Fl v 
flag to
.Nm newfs
in order to tell it to ignore this convention.
.\"
.It 
Plexes do not need to be assigned explicit names.  By default, a plex name is
the name of the volume followed by the letters \f(CW.p\fR and the number of the
plex.  For example, the plexes of volume
.Ar vol3
are called
.Ar vol3.p0 ,
.Ar vol3.p1
and so on.  These names can be overridden, but it is not recommended.
.br
.It
Like plexes, subdisks are assigned names automatically, and explicit naming is
discouraged.  A subdisk name is the name of the plex followed by the letters
\f(CW.s\fR and a number identifying the subdisk.  For example, the subdisks of
plex
.Ar vol3.p0
are called
.Ar vol3.p0.s0 ,
.Ar vol3.p0.s1
and so on.
.br
.It
By contrast, 
.Nm drives
must be named.  This makes it possible to move a drive to a different location
and still recognize it automatically.  Drive names may be up to 32 characters
long.
.El
.Pp
EXAMPLE
.Pp
Assume the 
.Nm
objects described in the section CONFIGURATION FILE in
.Xr vinum 8 .
The directory
.Ar /dev/vinum
looks like:
.Bd -unfilled -offset indent
# ls -lR /dev/vinum/ /dev/rvinum
total 5
brwxr-xr--  1 root  wheel   25,   2 Mar 30 16:08 concat
brwx------  1 root  wheel   25, 0x40000000 Mar 30 16:08 control
drwxrwxrwx  2 root  wheel       512 Mar 30 16:08 drive
drwxrwxrwx  2 root  wheel       512 Mar 30 16:08 plex
drwxrwxrwx  2 root  wheel       512 Mar 30 16:08 rvol
drwxrwxrwx  2 root  wheel       512 Mar 30 16:08 sd
brwxr-xr--  1 root  wheel   25,   3 Mar 30 16:08 strcon
brwxr-xr--  1 root  wheel   25,   1 Mar 30 16:08 stripe
brwxr-xr--  1 root  wheel   25,   0 Mar 30 16:08 tinyvol
drwxrwxrwx  7 root  wheel       512 Mar 30 16:08 vol
brwxr-xr--  1 root  wheel   25,   4 Mar 30 16:08 vol5

/dev/vinum/drive:
total 0
brw-r-----  1 root  operator    4,  15 Oct 21 16:51 drive2
brw-r-----  1 root  operator    4,  31 Oct 21 16:51 drive4

/dev/vinum/plex:
total 0
brwxr-xr--  1 root  wheel   25, 0x10000002 Mar 30 16:08 concat.p0
brwxr-xr--  1 root  wheel   25, 0x10010002 Mar 30 16:08 concat.p1
brwxr-xr--  1 root  wheel   25, 0x10000003 Mar 30 16:08 strcon.p0
brwxr-xr--  1 root  wheel   25, 0x10010003 Mar 30 16:08 strcon.p1
brwxr-xr--  1 root  wheel   25, 0x10000001 Mar 30 16:08 stripe.p0
brwxr-xr--  1 root  wheel   25, 0x10000000 Mar 30 16:08 tinyvol.p0
brwxr-xr--  1 root  wheel   25, 0x10000004 Mar 30 16:08 vol5.p0
brwxr-xr--  1 root  wheel   25, 0x10010004 Mar 30 16:08 vol5.p1

/dev/vinum/rvol:
total 0
crwxr-xr--  1 root  wheel   91,   2 Mar 30 16:08 concat
crwxr-xr--  1 root  wheel   91,   3 Mar 30 16:08 strcon
crwxr-xr--  1 root  wheel   91,   1 Mar 30 16:08 stripe
crwxr-xr--  1 root  wheel   91,   0 Mar 30 16:08 tinyvol
crwxr-xr--  1 root  wheel   91,   4 Mar 30 16:08 vol5

/dev/vinum/sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000002 Mar 30 16:08 concat.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100002 Mar 30 16:08 concat.p0.s1
brwxr-xr--  1 root  wheel   25, 0x20010002 Mar 30 16:08 concat.p1.s0
brwxr-xr--  1 root  wheel   25, 0x20000003 Mar 30 16:08 strcon.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100003 Mar 30 16:08 strcon.p0.s1
brwxr-xr--  1 root  wheel   25, 0x20010003 Mar 30 16:08 strcon.p1.s0
brwxr-xr--  1 root  wheel   25, 0x20110003 Mar 30 16:08 strcon.p1.s1
brwxr-xr--  1 root  wheel   25, 0x20000001 Mar 30 16:08 stripe.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100001 Mar 30 16:08 stripe.p0.s1
brwxr-xr--  1 root  wheel   25, 0x20000000 Mar 30 16:08 tinyvol.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100000 Mar 30 16:08 tinyvol.p0.s1
brwxr-xr--  1 root  wheel   25, 0x20000004 Mar 30 16:08 vol5.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100004 Mar 30 16:08 vol5.p0.s1
brwxr-xr--  1 root  wheel   25, 0x20010004 Mar 30 16:08 vol5.p1.s0
brwxr-xr--  1 root  wheel   25, 0x20110004 Mar 30 16:08 vol5.p1.s1

/dev/vinum/vol:
total 5
brwxr-xr--  1 root  wheel   25,   2 Mar 30 16:08 concat
drwxr-xr-x  4 root  wheel       512 Mar 30 16:08 concat.plex
brwxr-xr--  1 root  wheel   25,   3 Mar 30 16:08 strcon
drwxr-xr-x  4 root  wheel       512 Mar 30 16:08 strcon.plex
brwxr-xr--  1 root  wheel   25,   1 Mar 30 16:08 stripe
drwxr-xr-x  3 root  wheel       512 Mar 30 16:08 stripe.plex
brwxr-xr--  1 root  wheel   25,   0 Mar 30 16:08 tinyvol
drwxr-xr-x  3 root  wheel       512 Mar 30 16:08 tinyvol.plex
brwxr-xr--  1 root  wheel   25,   4 Mar 30 16:08 vol5
drwxr-xr-x  4 root  wheel       512 Mar 30 16:08 vol5.plex

/dev/vinum/vol/concat.plex:
total 2
brwxr-xr--  1 root  wheel   25, 0x10000002 Mar 30 16:08 concat.p0
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 concat.p0.sd
brwxr-xr--  1 root  wheel   25, 0x10010002 Mar 30 16:08 concat.p1
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 concat.p1.sd

/dev/vinum/vol/concat.plex/concat.p0.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000002 Mar 30 16:08 concat.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100002 Mar 30 16:08 concat.p0.s1

/dev/vinum/vol/concat.plex/concat.p1.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20010002 Mar 30 16:08 concat.p1.s0

/dev/vinum/vol/strcon.plex:
total 2
brwxr-xr--  1 root  wheel   25, 0x10000003 Mar 30 16:08 strcon.p0
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 strcon.p0.sd
brwxr-xr--  1 root  wheel   25, 0x10010003 Mar 30 16:08 strcon.p1
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 strcon.p1.sd

/dev/vinum/vol/strcon.plex/strcon.p0.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000003 Mar 30 16:08 strcon.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100003 Mar 30 16:08 strcon.p0.s1

/dev/vinum/vol/strcon.plex/strcon.p1.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20010003 Mar 30 16:08 strcon.p1.s0
brwxr-xr--  1 root  wheel   25, 0x20110003 Mar 30 16:08 strcon.p1.s1

/dev/vinum/vol/stripe.plex:
total 1
brwxr-xr--  1 root  wheel   25, 0x10000001 Mar 30 16:08 stripe.p0
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 stripe.p0.sd

/dev/vinum/vol/stripe.plex/stripe.p0.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000001 Mar 30 16:08 stripe.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100001 Mar 30 16:08 stripe.p0.s1

/dev/vinum/vol/tinyvol.plex:
total 1
brwxr-xr--  1 root  wheel   25, 0x10000000 Mar 30 16:08 tinyvol.p0
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 tinyvol.p0.sd

/dev/vinum/vol/tinyvol.plex/tinyvol.p0.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000000 Mar 30 16:08 tinyvol.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100000 Mar 30 16:08 tinyvol.p0.s1

/dev/vinum/vol/vol5.plex:
total 2
brwxr-xr--  1 root  wheel   25, 0x10000004 Mar 30 16:08 vol5.p0
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 vol5.p0.sd
brwxr-xr--  1 root  wheel   25, 0x10010004 Mar 30 16:08 vol5.p1
drwxr-xr-x  2 root  wheel       512 Mar 30 16:08 vol5.p1.sd

/dev/vinum/vol/vol5.plex/vol5.p0.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20000004 Mar 30 16:08 vol5.p0.s0
brwxr-xr--  1 root  wheel   25, 0x20100004 Mar 30 16:08 vol5.p0.s1

/dev/vinum/vol/vol5.plex/vol5.p1.sd:
total 0
brwxr-xr--  1 root  wheel   25, 0x20010004 Mar 30 16:08 vol5.p1.s0
brwxr-xr--  1 root  wheel   25, 0x20110004 Mar 30 16:08 vol5.p1.s1

/dev/rvinum:
crwxr-xr--  1 root  wheel   91,   2 Mar 30 16:08 rconcat
crwxr-xr--  1 root  wheel   91,   3 Mar 30 16:08 rstrcon
crwxr-xr--  1 root  wheel   91,   1 Mar 30 16:08 rstripe
crwxr-xr--  1 root  wheel   91,   0 Mar 30 16:08 rtinyvol
crwxr-xr--  1 root  wheel   91,   4 Mar 30 16:08 rvol5
.Ed
.Pp
In the case of unattached plexes and subdisks, the naming is reversed.  Subdisks
are named after the disk on which they are located, and plexes are named after
the subdisk.  
.\" XXX
.Nm This mapping is still to be determined.
.Ss OBJECT STATES
.Pp
Each
.Nm
object has a \fIstate\fR associated with it. 
.Nm
uses this state to determine the handling of the object.
.Pp
.Ss VOLUME STATES
Volumes may have the following states:
.sp
.ne 1i
.TB "Volume states"
.TS H
box,center,tab(#) ;
lfCWp9 | lw65 .
State#Meaning
=
.TH N
volume_unallocated#T{
present but unused.  This will not normally be seen from a user perspective.
T}
volume_uninit#T{
In the process of being created.
T}
volume_down#T{
The volume is inaccessible.
T}
volume_up#T{
The volume is up and functional, but not all plexes may be available.
T}

.TE
.TS H
box,center,tab(#) ;
lfCWp9 | lw65 .
State#Meaning
=
.TH N
volume_unallocated#T{
present but unused.  This will not normally be seen from a user perspective.
T}
.if t .sp .4v
.if n .sp 1
volume_uninit#T{
In the process of being created.
T}
.if t .sp .4v
.if n .sp 1
volume_down#T{
The volume is inaccessible.
T}
.if t .sp .4v
.if n .sp 1
volume_up#T{
The volume is up and functional, but not all plexes may be available.
T}
.if t .sp .4v
.if n .sp 1
.TE
.sp 2v
.Ss "PLEX STATES"
Plexes may have the following states:
.sp
.ne 1i
.TB "Plex states"
.TS H
box,center,tab(#) ;
lfCWp9 | lw65 .
State#Meaning
=
.TH N
plex_unallocated#T{
An empty entry, not a plex at all.
T}
.if t .sp .4v
.if n .sp 1
plex_checkup#T{
Temporary state: check subordinate subdisks to decide which state we can take.
The options are plex_error (no subdisks), plex_corrupted (not all subdisks, and
we were down), plex_degraded (not all subdisks, and we were up), plex_up (all
subdisks)
T}
.if t .sp .4v
.if n .sp 1
plex_checkdown#T{
Temporary state: check our previous state to decide whether we should go to down
or error state.
T}
.if t .sp .4v
.if n .sp 1
plex_uninit#T{
A plex entry which has not been created completely.  Some fields may be empty.
T}
.if t .sp .4v
.if n .sp 1
plex_init#T{
All fields are correct, and the disk has been
updated, but there is no data on the disk.
T}
.if t .sp .4v
.if n .sp 1
plex_error#T{
A plex which has gone completely down because of I/O errors.
T}
.if t .sp .4v
.if n .sp 1
plex_down#T{
A plex which has been taken down by the
administrator.
T}
.if t .sp .4v
.if n .sp 1
#T{
The remaining states represent plexes which are
at least partially up.  Keep these separate so that
they can be checked more easily.
T}
.if t .sp .4v
.if n .sp 1
plex_corrupted#T{
A plex entry which is at least partially up.  Not all subdisks are available,
and an inconsistency has occurred.  If no other plex is uncorrupted, the volume
is no longer consistent.
T}
.if t .sp .4v
.if n .sp 1
plex_degraded#T{
A plex entry which is at least partially up.  Not all subdisks are available,
but so far no inconsistency has occurred (this will change with the first write
to the address space occupied by a defective subdisk).  This state includes the
condition where a subdisk is being copied.
T}
.if t .sp .4v
.if n .sp 1
plex_flaky#T{
A plex which is really up, but which has a reborn subdisk which we don't
completely trust, and which we don't want to read if we can avoid it
T}
.if t .sp .4v
.if n .sp 1
plex_up#T{
A plex entry which is completely up.  All subdisks
are up.
T}
.if t .sp .4v
.if n .sp 1
.TE
.sp 2v
.Ss "SUBDISK STATES"
Subdisks can have the following states:
.sp
.ne 1i
.TB "Subdisk states"
.TS H
box,center,tab(#) ;
lfCWp9 | lw65 .
State#Meaning
=
.TH N
sd_unallocated#T{
An empty entry, not a subdisk at all.
T}
.if t .sp .4v
.if n .sp 1
sd_uninit#T{
A subdisk entry which has not been created
completely.  Some fields may be empty.
T}
.if t .sp .4v
.if n .sp 1
sd_init#T{
A subdisk entry which has been created completely.
All fields are correct, but the disk hasn't
been updated.
T}
.if t .sp .4v
.if n .sp 1
sd_empty#T{
A subdisk entry which has been created completely.
All fields are correct, and the disk has been
updated, but there is no data on the disk.
T}
.if t .sp .4v
.if n .sp 1
sd_obsolete#T{
A subdisk entry which has been created completely.
All fields are correct, the disk has been updated,
and the data was valid, but since then the drive
has gone down, and as a result updates have been
missed.
T}
.if t .sp .4v
.if n .sp 1
sd_stale#T{
A subdisk entry which has been created completely.
All fields are correct, the disk has been updated,
and the data was valid, but since then the drive
has gone down, updates have been lost, and then
the drive came up again.
T}
.if t .sp .4v
.if n .sp 1
#T{
The following states represent valid, inaccessible data
T}
.if t .sp .4v
.if n .sp 1
sd_crashed#T{
A subdisk entry which has been created completely.
All fields are correct, the disk has been updated,
and the data was valid, but since then the drive
has gone down.   No attempt has been made to write
to the subdisk since the crash.
T}
.if t .sp .4v
.if n .sp 1
sd_down#T{
A subdisk entry which was up, which contained
valid data, and which was taken down by the
administrator.  The data is valid.
T}
.if t .sp .4v
.if n .sp 1
sd_reborn#T{
A subdisk entry which has been created completely.
All fields are correct, the disk has been updated,
and the data was valid, but since then the drive
has gone down and up again.  No updates were lost,
but it is possible that the subdisk has been
damaged.  We won't read from this subdisk if we
have a choice.
T}
.if t .sp .4v
.if n .sp 1
sd_up#T{
A subdisk entry which has been created completely.
All fields are correct, the disk has been updated,
and the data is valid.
T}
.if t .sp .4v
.if n .sp 1
.TE
.sp 2v
.Ss "DRIVE STATES"
Drives can have the following states:
.sp
.ne 1i
.TB "Drive states"
.TS H
box,center,tab(#) ;
lfCWp9 | lw65 .
State#Meaning
=
.TH N
drive_unallocated#T{
Unused entry.
T}
.if t .sp .4v
.if n .sp 1
drive_uninit#T{
just mentioned in some other config entry.
T}
.if t .sp .4v
.if n .sp 1
drive_down#T{
not accessible
T}
.if t .sp .4v
.if n .sp 1
drive_coming_up#T{
in the process of being brought up
T}
.if t .sp .4v
.if n .sp 1
drive_up#up and running
.TE
.sp 2v
.Sh BUGS AND OMISSIONS
Many.  
.Nm vinum
is currently in beta test.  Please report any bugs not in the list below to
.Ar <grog@lemis.com> .
.sp
The following functions are known to be deficient or not implemented:
.Bl -bullet
.It
It is necessary to initialize RAID-5 plexes.  Failure to do so will not impede
normal operation, but it will cause complete corruption if one of the disks
should fail.  I don't know any good way to enforce this initialization (or the
even slower alternative of rebuilding the parity blocks).  If anybody has a good
idea, I'd be grateful for input.
.It
Detection of differences between the version of the kernel and the LKM is not
yet implemented.
.El
.Sh AUTHOR
Greg Lehey
.Pa <grog@lemis.com> .
.Sh HISTORY
.Nm vinum
first appeared in FreeBSD 3.0.
.Sh SEE ALSO
.Xr vinum 8 ,
.Xr disklabel 5 ,
.Xr disklabel 8 .