freebsd-skq/share/man/man4/vinum.4

.\"  Hey, Emacs, edit this file in -*- nroff-fill -*- mode
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.\" $Id: vinum.4,v 1.8 1999/01/15 03:54:40 grog Exp grog $
.\"
.Dd 22 July 1998
.Dt vinum 4
.Os FreeBSD
.Sh NAME
.Nm vinum
.Nd Logical Volume Manager
.Sh SYNOPSIS
.Cd "kldload vinum"
.Cd "kldload Vinum"
.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
is currently supplied as a kernel loadable module (kld), and does not require
configuration.  As with other klds, it is absolutely necessary to match the kld
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
Normally, you start a configured version of
.Nm
at boot time.  Set the variable
.Ar vinum_slices
in
.Ar /etc/rc.conf
to indicate the slices on which 
.Nm
drives are located.  For example, if you have 
.Nm
drives on
.Ar /dev/da1h ,
.Ar /dev/da2h ,
.Ar /dev/da3h ,
.Ar /dev/da4h 
and
.Ar /dev/da5h ,
you would set the variable to:
.Bd -literal
vinum_slices="/dev/da1h /dev/da2h /dev/da3h /dev/da4h /dev/da5h"
.Ed
.Pp
.Sh VINUM INSTALLATION
The freely available version of the
.Nm
kld is called 
.Pa /modules/vinum.ko ,
and the RAID-5 version is
.Pa /modules/Vinum.o .
To load the module:
.Pp
.Bd -unfilled -offset indent
# kldload vinum
.Ed
.Pp
.Nm vinum(8)
also automatically loads the kld module if it is not yet loaded.
.Pp
After loading
.Nm vinum ,
it must be confiugred.  In an existing installation, the following command reads
the configuration an existing set of disks:
.Bd -unfilled -offset indent
# vinum read /dev/da1h /dev/da2h /dev/da3h /dev/da4h /dev/da5h /dev/da6h
.Ed
.sp
This command must specify all of the devices used by
.Nm vinum .
.Nm vinum(8) 
reads the configuration from the device with the newest configuration file, then
updates it if necessary with additional information from successively older
configurations.  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 kld, first find the
.Ar Id
field in 
.Pa kldstat:
.Bd -unfilled -offset indent
# kldstat
Id Refs Address    Size     Name
 1    2 0xf0100000 1c7de8   kernel
 2    1 0xf0f5b000 b0000    Vinum.ko
.Ed
.Pp
To unload the module, use
.Pa kldunload:
.Bd -unfilled -offset indent
# kldunload -n Vinum
.Ed
.Pp
The kld 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 kld 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
.Bl -hang -width 14n
.It volume_down
The volume is completely inaccessible.
.It volume_up
The volume is up and at least partially functional.  Not all plexes may be
available.
.El
.Ss "PLEX STATES"
Plexes may have the following states:
.sp
.ne 1i
.Bl -hang -width 14n
.It faulty
A plex which has gone completely down because of I/O errors.
.It down
A plex which has been taken down by the administrator.
.It initializing
A plex which is being initialized.
.sp
The remaining states represent plexes which are at least partially up.
.It corrupt
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.
.It degraded
A RAID-5 plex entry which is accessible, but one subdisk is down, requiring
recovery for many I/O requests.
.It flaky
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.
.It up
A plex entry which is completely up.  All subdisks are up.
.El
.sp 2v
.Ss "SUBDISK STATES"
Subdisks can have the following states:
.sp
.ne 1i
.Bl -hang -width 14n
.It empty
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.
.It initializing
A subdisk entry which has been created completely and which is currently being
initialized.
.sp
The following states represent invalid data.
.It obsolete
A subdisk entry which has been created completely.  All fields are correct, the
config on disk has been updated, and the data was valid, but since then the
drive has been taken down, and as a result updates have been missed.
.It stale
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 been
crashed and updates have been lost.
.sp
The following states represent valid, inaccessible data.
.It crashed
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, so the
data is valid.
.It down
A subdisk entry which was up, which contained valid data, and which was taken
down by the administrator.  The data is valid.
.It reviving
The subdisk is currently in the process of being revived.  We can write but not
read.
.sp
The following states represent accessible subdisks with valid data.
.It reborn
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.  If this
is the only subdisk which covers this address space in the plex, we set its
state to up under these circumstances, so this status implies that there is
another subdisk to fulfil the request.
.It up
A subdisk entry which has been created completely.  All fields are correct, the
disk has been updated, and the data is valid.
.El
.sp 2v
.Ss "DRIVE STATES"
Drives can have the following states:
.sp
.ne 1i
.Bl -hang -width 14n
.It down
The drive is not accessible.
.It up
The drive is up and running.
.El
.sp 2v
.Sh BUGS AND OMISSIONS
.Bl -enum
.It
.Nm
is a new product.  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.
.It
It is possible to unload the
.Nm
module with the
.Nm kldunload
command.  This is buggy, and the only reason it is present at all is to make it
easier for people testing the system: the alternative is a reboot.  It works
about 80% of the time: expect about one panic every five unloads.
.It
It is possible to configure
.Nm
statically, but it has never been tested in this form.  Don't even bother to
report the problem if you have trouble with a static
.Nm
pseudo-device, unless you can also repeat it with the kld module.
.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 kld 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 .