228 lines
6.4 KiB
Groff
228 lines
6.4 KiB
Groff
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.\" Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" Copyright (c) 2005 Ivan Voras <ivoras@FreeBSD.org>
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.\" All rights reserved.
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 8, 2006
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.Dt GVIRSTOR 8
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.Os
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.Sh NAME
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.Nm gvirstor
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.Nd "provides virtual data storage geom"
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.Sh SYNOPSIS
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.Nm
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.Cm label
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.Op Fl hv
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.Op Fl s Ar virsize
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.Op Fl m Ar chunksize
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.Ar name
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.Ar prov ...
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.Nm
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.Cm stop
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.Op Fl fv
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.Ar name ...
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.Nm
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.Cm add
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.Op Fl vh
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.Ar name prov ...
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.Nm
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.Cm remove
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.Op Fl v
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.Ar name prov ...
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.Nm
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.Cm clear
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.Op Fl v
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.Ar prov ...
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.Nm
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.Cm dump
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.Ar prov ...
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.Nm
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.Cm list
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.Nm
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.Cm status
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.Nm
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.Cm load
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.Nm
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.Cm unload
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.Sh DESCRIPTION
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The
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.Nm
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utility is used for setting up a storage device of arbitrary large size (for example,
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several TB), consisting of an arbitrary number of physical storage devices with
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total size <= the virtual size. Data for the virtual devices will be allocated from
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physical devices on demand. In short, this is the virtual storage functionality.
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The first argument to
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.Nm
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indicates an action to be performed:
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.Bl -tag -width ".Cm destroy"
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.It Cm label
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Set up a virtual device from the given components with the specified
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.Ar name .
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Metadata are stored in the last sector of every component.
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Argument
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.Ar virsize
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is the size of new virtual device, with default being 2 TiB (2097152 MiB).
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Argument
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.Ar chunksize
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is the chunk size, with default being 4 MiB (4096 KiB).
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The default is thus "-s 2097152 -m 4096".
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.It Cm stop
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Turn off an existing virtual device by its
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.Ar name .
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This command does not touch on-disk metadata.
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As with other GEOM classes, stopped geoms cannot be started manually.
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.It Cm add
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Adds new components to existing virtual device by its
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.Ar name .
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The specified virstor device must exist and be active (i.e.
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module loaded, device present in /dev).
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.It Cm remove
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Removes components from existing virtual device by its
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.Ar name .
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Only unallocated providers can be removed.
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.It Cm clear
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Clear metadata on the given providers.
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.It Cm dump
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Dump metadata stored on the given providers.
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.It Cm list
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See
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.Xr geom 8 .
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.It Cm status
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See
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.Xr geom 8 .
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.It Cm load
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See
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.Xr geom 8 .
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.It Cm unload
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See
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.Xr geom 8 .
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.El
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.Pp
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Additional options:
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.Bl -tag -width ".Fl f"
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.It Fl f
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Force the removal of the specified virtual device.
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.It Fl h
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Hardcode providers' names in metadata.
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.It Fl v
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Be more verbose.
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.El
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.Sh EXIT STATUS
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Exit status is 0 on success, and 1 if the command fails.
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.Sh EXAMPLES
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The following example shows how to create a virtual device of default size
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(2 TiB), of default chunk (extent) size (4 MiB), with two physical devices for
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backing storage.
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.Bd -literal -offset indent
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gvirstor label -v mydata /dev/ad4 /dev/ad6
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newfs /dev/virstor/mydata
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.Ed
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.Pp
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From now on, the virtual device will be available via the
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.Pa /dev/virstor/mydata
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device entry.
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To add a new physical device / provider to an active virstor device:
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.Bd -literal -offset indent
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gvirstor add mydata ad8
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.Ed
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.Pp
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This will add physical storage (from ad8) to
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.Pa /dev/virstor/mydata
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device.
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To see device status information (including how much physical storage
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is still available for the virtual device), use:
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.Bd -literal -offset indent
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gvirstor list
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.Ed
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.Pp
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All standard
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.Xr geom 8
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subcommands (e.g. "status", "help") are also supported.
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.Sh SYSCTLs
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.Nm
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has several
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.Xr sysctl 8
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tunable variables.
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.Bd -literal -offset indent
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.Pa int kern.geom.virstor.debug
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.Ed
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.Pp
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This sysctl controls verbosity of the kernel module, in the range
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1 to 15. Messages that are marked with higher verbosity levels than
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this are supressed. Default value is 5 and it's not
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recommented to set this tunable to less than 2, because level 1 messages
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are error events, and level 2 messages are system warnings.
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.Bd -literal -offset indent
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.Pa int kern.geom.virstor.chunk_watermark
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.Ed
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.Pp
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Value in this sysctl sets warning watermark level for physical chunk usage
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on a single component. The warning is issued when a virstor component
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has less than this many free chunks (default 100).
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.Bd -literal -offset indent
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.Pa int kern.geom.virstor.component_watermark
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.Ed
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.Pp
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Value in this sysctl sets warning watermark level for component usage.
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The warning is issed when there are less than this many unallocated
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components (default is 1).
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.Pp
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All these sysctls are also available as
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.Xr loader 8
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tunables.
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.Sh LOG MESSAGES
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.Nm
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kernel module issues log messages with prefixes in standardised format,
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which is useful for log message filtering and dispatching. Each message
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line begins with
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.Bd -literal -offset indent
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.Pa GEOM_VIRSTOR[%d]:
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.Ed
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.Pp
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The number (%d) is message verbosity / importance level, in the range
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1 to 15. If a message filtering, dispatching or operator alert system is
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used, it is recommended that messages with levels 1 and 2 be taken
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seriously (for example, to catch out-of-space conditions as set by
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watermark sysctls).
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr geom 8 ,
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.Xr newfs 8 ,
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.Xr fstab 5 ,
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.Xr glabel 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Fx 7.0 .
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.Sh BUGS
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Commands "add" and "remove" contain unavoidable critical sections
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which may make the virstor device unusable if a power failure (or
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other disruptive event) happens during their execution.
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It's recommended to run them when the system is quiescent.
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.Sh AUTHOR
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.An Ivan Voras Aq ivoras@FreeBSD.org
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Sponsored by Google Summer of Code 2006
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