696 lines
24 KiB
Groff
696 lines
24 KiB
Groff
.\" Hey, Emacs, edit this file in -*- nroff-fill -*- mode
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.\" $NetBSD: ccd.4,v 1.5 1995/10/09 06:09:09 thorpej Exp $
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.\"-
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.\" Copyright (c) 1997, 1998
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.\" Nan Yang Computer Services Limited. All rights reserved.
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.\"
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.\" This software is distributed under the so-called ``Berkeley
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.\" License'':
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Nan Yang Computer
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.\" Services Limited.
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.\" 4. Neither the name of the Company nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" This software is provided ``as is'', and any express or implied
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.\" warranties, including, but not limited to, the implied warranties of
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.\" merchantability and fitness for a particular purpose are disclaimed.
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.\" In no event shall the company or contributors be liable for any
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.\" direct, indirect, incidental, special, exemplary, or consequential
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.\" damages (including, but not limited to, procurement of substitute
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.\" goods or services; loss of use, data, or profits; or business
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.\" interruption) however caused and on any theory of liability, whether
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.\" in contract, strict liability, or tort (including negligence or
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.\" otherwise) arising in any way out of the use of this software, even if
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.\" advised of the possibility of such damage.
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.\"
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.\" $Id: vinum.4,v 1.8 1999/01/15 03:54:40 grog Exp grog $
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.\"
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.Dd 22 July 1998
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.Dt vinum 4
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.Os FreeBSD
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.Sh NAME
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.Nm vinum
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.Nd Logical Volume Manager
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.Sh SYNOPSIS
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.Cd "kldload vinum"
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.Cd "kldload Vinum"
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.Sh DESCRIPTION
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.Nm
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is a logical volume manager inspired by, but not derived from, the Veritas
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Volume Manager. It provides the following features:
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.Bl -bullet
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.It
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It provides device-independent logical disks, called \fIvolumes\fP. Volumes are
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not restricted to the size of any disk on the system.
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.It
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The volumes consist of one or more \fIplexes\fP, each of which contain the
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entire address space of a volume. This represents an implementation of RAID-1
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(mirroring). Multiple plexes can also be used for
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.\" XXX What about sparse plexes? Do we want them?
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.if t .sp
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.Bl -bullet
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.It
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Increased read throughput.
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.Nm
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will read data from the least active disk, so if a volume has plexes on multiple
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disks, more data can be read in parallel.
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.Nm
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reads data from only one plex, but it writes data to all plexes.
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.It
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Increased reliability. By storing plexes on different disks, data will remain
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available even if one of the plexes becomes unavailable. In comparison with a
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RAID-5 plex (see below), using multiple plexes requires more storage space, but
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gives better performance, particularly in the case of a drive failure.
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.It
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Additional plexes can be used for on-line data reorganization. By attaching an
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additional plex and subsequently detaching one of the older plexes, data can be
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moved on-line without compromising access.
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.It
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An additional plex can be used to obtain a consistent dump of a file system. By
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attaching an additional plex and detaching at a specific time, the detached plex
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becomes an accurate snapshot of the file system at the time of detachment.
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.\" Make sure to flush!
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.El
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.It
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Each plex consists of one or more logical disk slices, called \fIsubdisks\fP.
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Subdisks are defined as a contiguous block of physical disk storage. A plex may
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consist of any reasonable number of subdisks (in other words, the real limit is
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not the number, but other factors, such as memory and performance, associated
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with maintaining a large number of subdisks).
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.It
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A number of mappings between subdisks and plexes are available:
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.Bl -bullet
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.It
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\fIConcatenated plexes\fP\| consist of one or more subdisks, each of which
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is mapped to a contiguous part of the plex address space.
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.It
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\fIStriped plexes\fP\| consist of two or more subdisks of equal size. The file
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address space is mapped in \fIstripes\fP, integral fractions of the subdisk
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size. Consecutive plex address space is mapped to stripes in each subdisk in
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.if n turn.
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.if t \{\
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turn:
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.PS
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move right 2i
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down
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SD0: box
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SD1: box
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SD2: box
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"plex 0" at SD0.n+(0,.2)
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"subdisk 0" rjust at SD0.w-(.2,0)
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"subdisk 1" rjust at SD1.w-(.2,0)
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"subdisk 2" rjust at SD2.w-(.2,0)
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.PE
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.\}
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The subdisks of a striped plex must all be the same size.
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.It
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\fIRAID-5 plexes\fP\| require at least three equal-sized subdisks. They
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resemble striped plexes, except that in each stripe, one subdisk stores parity
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information. This subdisk changes in each stripe: in the first stripe, it is the
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first subdisk, in the second it is the second subdisk, etc. In the event of a
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single disk failure,
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.Nm
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will recover the data based on the information stored on the remaining subdisks.
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This mapping is particularly suited to read-intensive access. The subdisks of a
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RAID-5 plex must all be the same size.
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.\" Make sure to flush!
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.El
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.It
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.Nm Drives
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are the lowest level of the storage hierarchy. They represent disk special
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devices.
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.It
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.Nm
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offers automatic startup. Unlike UNIX file systems,
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.Nm
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volumes contain all the configuration information needed to ensure that they are
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started correctly when the subsystem is enabled. This is also a significant
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advantage over the Veritas\(tm File System. This feature regards the presence
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of the volumes. It does not mean that the volumes will be mounted
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automatically, since the standard startup procedures with
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.Pa /etc/fstab
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perform this function.
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.El
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.Sh KERNEL CONFIGURATION
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.Nm
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is currently supplied as a kernel loadable module (kld), and does not require
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configuration. As with other klds, it is absolutely necessary to match the kld
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to the version of the operating system. Failure to do so will cause
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.Nm
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to issue an error message and terminate.
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.Pp
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.Nm
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is currently available in two versions: a freely available version which does
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not contain RAID-5 functionality, and a full version including RAID-5
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functionality, which is available from Cybernet Systems
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Inc. (http://www.cybernet.com\fR).
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.Sh RUNNING VINUM
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Normally, you start a configured version of
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.Nm
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at boot time. Set the variable
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.Ar vinum_slices
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in
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.Ar /etc/rc.conf
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to indicate the slices on which
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.Nm
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drives are located. For example, if you have
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.Nm
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drives on
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.Ar /dev/da1h ,
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.Ar /dev/da2h ,
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.Ar /dev/da3h ,
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.Ar /dev/da4h
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and
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.Ar /dev/da5h ,
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you would set the variable to:
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.Bd -literal
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vinum_slices="/dev/da1h /dev/da2h /dev/da3h /dev/da4h /dev/da5h"
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.Ed
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.Pp
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.Sh VINUM INSTALLATION
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The freely available version of the
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.Nm
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kld is called
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.Pa /modules/vinum.ko ,
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and the RAID-5 version is
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.Pa /modules/Vinum.o .
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To load the module:
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.Pp
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.Bd -unfilled -offset indent
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# kldload vinum
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.Ed
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.Pp
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.Nm vinum(8)
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also automatically loads the kld module if it is not yet loaded.
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.Pp
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After loading
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.Nm vinum ,
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it must be confiugred. In an existing installation, the following command reads
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the configuration an existing set of disks:
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.Bd -unfilled -offset indent
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# vinum read /dev/da1h /dev/da2h /dev/da3h /dev/da4h /dev/da5h /dev/da6h
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.Ed
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.sp
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This command must specify all of the devices used by
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.Nm vinum .
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.Nm vinum(8)
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reads the configuration from the device with the newest configuration file, then
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updates it if necessary with additional information from successively older
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configurations. These commands are normally embedded in the startup file
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.Pa /etc/rc .
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.Pp
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See
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.Xr vinum 8
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for information on how to create a
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.Nm
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configuration.
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.Pp
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To unload the kld, first find the
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.Ar Id
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field in
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.Pa kldstat:
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.Bd -unfilled -offset indent
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# kldstat
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Id Refs Address Size Name
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1 2 0xf0100000 1c7de8 kernel
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2 1 0xf0f5b000 b0000 Vinum.ko
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.Ed
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.Pp
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To unload the module, use
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.Pa kldunload:
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.Bd -unfilled -offset indent
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# kldunload -n Vinum
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.Ed
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.Pp
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The kld can only be unloaded when idle, in other words when no volumes are
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mounted and no other instances of the
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.Nm
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program are active. Unloading the kld does not harm the data in the volumes.
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.Ss CONFIGURING AND STARTING OBJECTS
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Use the
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.Xr vinum 8
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utility to configure and start
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.Nm
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objects.
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.Sh IOCTL CALLS
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.Pa ioctl
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calls are intended for the use of the
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.Nm
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configuration program only. The are described in the header file
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.Pa /sys/sys/vinumio.h
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.Ss DISK LABELS
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Conventional disk special devices have a
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.Em disk label
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in the second sector of the device. See
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.Xr disklabel 5
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for more details. This disk label describes the layout of the partitions within
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the device.
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.Nm
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does not subdivide volumes, so volumes do not contain a physical disk label.
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For convenience,
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.Nm
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implements the ioctl calls DIOCGDINFO (get disk label), DIOCGPART (get partition
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information), DIOCWDINFO (write partition information) and DIOCSDINFO (set
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partition information). DIOCGDINFO and DIOCGPART refer to an internal
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representation of the disk label which is not present on the volume. As a
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result, the
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.Fl r
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option of
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.Xr disklabel 8 ,
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which reads the ``raw disk'', will fail.
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.Pp
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In general,
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.Xr disklabel 8
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serves no useful purpose on a vinum volume. If you run it, it will show you
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three partitions, a, b and c, all the same except for the fstype, for example:
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.Bd -unfilled -offset
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3 partitions:
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# size offset fstype [fsize bsize bps/cpg]
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a: 2048 0 4.2BSD 1024 8192 0 # (Cyl. 0 - 0)
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b: 2048 0 swap # (Cyl. 0 - 0)
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c: 2048 0 unused 0 0 # (Cyl. 0 - 0)
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.Ed
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.Pp
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.Nm
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ignores the DIOCWDINFO and DIOCSDINFO ioctls, since there is nothing to change.
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As a result, any attempt to modify the disk label will be silently ignored.
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.Sh MAKING FILE SYSTEMS
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Since
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.Nm
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volumes do not contain partitions, the names do not need to conform to the
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standard rules for naming disk partitions. For a physical disk partition, the
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last letter of the device name specifies the partition identifier (a to h).
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.Nm
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volumes need not conform to this convention, but if they do not,
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.Nm newfs
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will complain that it cannot determine the partition. To solve this problem,
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use the
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.Fl v
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flag to
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.Nm newfs .
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.Sh OBJECT NAMING
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.Nm
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assigns default names to plexes and subdisks, although they may be overridden.
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We do not recommend overriding the default names. Experience with the
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.if t Veritas\(tm
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.if n Veritas(tm)
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volume manager, which allows arbitary naming of objects, has shown that this
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flexibility does not bring a significant advantage, and it can cause confusion.
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.sp
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Names may contain any non-blank character, but it is recommended to restrict
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them to letters, digits and the underscore characters. The names of volumes,
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plexes and subdisks may be up to 64 characters long, and the names of drives may
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up to 32 characters long. When choosing volume and plex names, bear in mind
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that automatically generated plex and subvolume names are longer than the
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name from which they are derived.
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.Bl -bullet
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.It
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When
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.Nm vinum(8)
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creates or deletes objects, it creates a directory
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.Ar /dev/vinum ,
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in which it makes device entries for each volume it finds. It also creates
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subdirectories,
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.Ar /dev/vinum/plex
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and
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.Ar /dev/vinum/sd ,
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in which it stores device entries for the plexes and subdisks. In addition, it
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creates two more directories,
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.Ar /dev/vinum/vol
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and
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.Ar /dev/vinum/drive ,
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in which it stores hierarchical information for volumes and drives.
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.It
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Unlike
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.Nm UNIX
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drives,
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.Nm
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volumes are not subdivided into partitions, and thus do not contain a disk
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label. Unfortunately, this confuses a number of utilities, notably
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.Nm newfs ,
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which normally tries to interpret the last letter of a
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.Nm
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volume name as a partition identifier. If you use a volume name which does not
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end in the letters
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.Ar a
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to
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.Ar c ,
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you must use the
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.Fl v
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flag to
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.Nm newfs
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in order to tell it to ignore this convention.
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.\"
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.It
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Plexes do not need to be assigned explicit names. By default, a plex name is
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the name of the volume followed by the letters \f(CW.p\fR and the number of the
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plex. For example, the plexes of volume
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.Ar vol3
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are called
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.Ar vol3.p0 ,
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.Ar vol3.p1
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and so on. These names can be overridden, but it is not recommended.
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.br
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.It
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Like plexes, subdisks are assigned names automatically, and explicit naming is
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discouraged. A subdisk name is the name of the plex followed by the letters
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\f(CW.s\fR and a number identifying the subdisk. For example, the subdisks of
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plex
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.Ar vol3.p0
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are called
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.Ar vol3.p0.s0 ,
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.Ar vol3.p0.s1
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and so on.
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.br
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.It
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By contrast,
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.Nm drives
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must be named. This makes it possible to move a drive to a different location
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and still recognize it automatically. Drive names may be up to 32 characters
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long.
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.El
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.Pp
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EXAMPLE
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.Pp
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Assume the
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.Nm
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objects described in the section CONFIGURATION FILE in
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.Xr vinum 8 .
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The directory
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.Ar /dev/vinum
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looks like:
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.Bd -unfilled -offset indent
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# ls -lR /dev/vinum/ /dev/rvinum
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total 5
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brwxr-xr-- 1 root wheel 25, 2 Mar 30 16:08 concat
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brwx------ 1 root wheel 25, 0x40000000 Mar 30 16:08 control
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drwxrwxrwx 2 root wheel 512 Mar 30 16:08 drive
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drwxrwxrwx 2 root wheel 512 Mar 30 16:08 plex
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drwxrwxrwx 2 root wheel 512 Mar 30 16:08 rvol
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drwxrwxrwx 2 root wheel 512 Mar 30 16:08 sd
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brwxr-xr-- 1 root wheel 25, 3 Mar 30 16:08 strcon
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brwxr-xr-- 1 root wheel 25, 1 Mar 30 16:08 stripe
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brwxr-xr-- 1 root wheel 25, 0 Mar 30 16:08 tinyvol
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drwxrwxrwx 7 root wheel 512 Mar 30 16:08 vol
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brwxr-xr-- 1 root wheel 25, 4 Mar 30 16:08 vol5
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/dev/vinum/drive:
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total 0
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brw-r----- 1 root operator 4, 15 Oct 21 16:51 drive2
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brw-r----- 1 root operator 4, 31 Oct 21 16:51 drive4
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/dev/vinum/plex:
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total 0
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brwxr-xr-- 1 root wheel 25, 0x10000002 Mar 30 16:08 concat.p0
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brwxr-xr-- 1 root wheel 25, 0x10010002 Mar 30 16:08 concat.p1
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brwxr-xr-- 1 root wheel 25, 0x10000003 Mar 30 16:08 strcon.p0
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brwxr-xr-- 1 root wheel 25, 0x10010003 Mar 30 16:08 strcon.p1
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brwxr-xr-- 1 root wheel 25, 0x10000001 Mar 30 16:08 stripe.p0
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brwxr-xr-- 1 root wheel 25, 0x10000000 Mar 30 16:08 tinyvol.p0
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brwxr-xr-- 1 root wheel 25, 0x10000004 Mar 30 16:08 vol5.p0
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brwxr-xr-- 1 root wheel 25, 0x10010004 Mar 30 16:08 vol5.p1
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/dev/vinum/rvol:
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total 0
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crwxr-xr-- 1 root wheel 91, 2 Mar 30 16:08 concat
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crwxr-xr-- 1 root wheel 91, 3 Mar 30 16:08 strcon
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crwxr-xr-- 1 root wheel 91, 1 Mar 30 16:08 stripe
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crwxr-xr-- 1 root wheel 91, 0 Mar 30 16:08 tinyvol
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crwxr-xr-- 1 root wheel 91, 4 Mar 30 16:08 vol5
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/dev/vinum/sd:
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total 0
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brwxr-xr-- 1 root wheel 25, 0x20000002 Mar 30 16:08 concat.p0.s0
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brwxr-xr-- 1 root wheel 25, 0x20100002 Mar 30 16:08 concat.p0.s1
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brwxr-xr-- 1 root wheel 25, 0x20010002 Mar 30 16:08 concat.p1.s0
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brwxr-xr-- 1 root wheel 25, 0x20000003 Mar 30 16:08 strcon.p0.s0
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brwxr-xr-- 1 root wheel 25, 0x20100003 Mar 30 16:08 strcon.p0.s1
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brwxr-xr-- 1 root wheel 25, 0x20010003 Mar 30 16:08 strcon.p1.s0
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brwxr-xr-- 1 root wheel 25, 0x20110003 Mar 30 16:08 strcon.p1.s1
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brwxr-xr-- 1 root wheel 25, 0x20000001 Mar 30 16:08 stripe.p0.s0
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brwxr-xr-- 1 root wheel 25, 0x20100001 Mar 30 16:08 stripe.p0.s1
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brwxr-xr-- 1 root wheel 25, 0x20000000 Mar 30 16:08 tinyvol.p0.s0
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brwxr-xr-- 1 root wheel 25, 0x20100000 Mar 30 16:08 tinyvol.p0.s1
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brwxr-xr-- 1 root wheel 25, 0x20000004 Mar 30 16:08 vol5.p0.s0
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brwxr-xr-- 1 root wheel 25, 0x20100004 Mar 30 16:08 vol5.p0.s1
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brwxr-xr-- 1 root wheel 25, 0x20010004 Mar 30 16:08 vol5.p1.s0
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brwxr-xr-- 1 root wheel 25, 0x20110004 Mar 30 16:08 vol5.p1.s1
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/dev/vinum/vol:
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total 5
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brwxr-xr-- 1 root wheel 25, 2 Mar 30 16:08 concat
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drwxr-xr-x 4 root wheel 512 Mar 30 16:08 concat.plex
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|
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 .
|