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Add Greg Oster's man page for WAPBL. Still a work in progress, 

expect updates.

Thanks a lot to Greg for cribbing together the info and getting
this going.
This commit is contained in:
simonb 2008-07-31 08:28:17 +00:00
parent 64c83a728a
commit bc6528ab7a
3 changed files with 193 additions and 4 deletions
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4
distrib/sets/lists/man/mi
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@ -1,4 +1,4 @@
# $NetBSD: mi,v 1.1081 2008/07/22 21:08:00 dyoung Exp $
# $NetBSD: mi,v 1.1082 2008/07/31 08:28:17 simonb Exp $
#
# Note: don't delete entries from here - mark them as "obsolete" instead.
#
@ -1616,6 +1616,7 @@
./usr/share/man/cat4/vmnet.0 man-sys-catman .cat
./usr/share/man/cat4/vnd.0 man-sys-catman .cat
./usr/share/man/cat4/vr.0 man-sys-catman .cat
./usr/share/man/cat4/wapbl.0 man-sys-catman .cat
./usr/share/man/cat4/wd.0 man-sys-catman .cat
./usr/share/man/cat4/wdc.0 man-sys-catman .cat
./usr/share/man/cat4/wds.0 man-sys-catman .cat
@ -4189,6 +4190,7 @@
./usr/share/man/man4/vmnet.4 man-sys-man .man
./usr/share/man/man4/vnd.4 man-sys-man .man
./usr/share/man/man4/vr.4 man-sys-man .man
./usr/share/man/man4/wapbl.4 man-sys-man .man
./usr/share/man/man4/wd.4 man-sys-man .man
./usr/share/man/man4/wdc.4 man-sys-man .man
./usr/share/man/man4/wds.4 man-sys-man .man

6
share/man/man4/Makefile
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# $NetBSD: Makefile,v 1.468 2008/07/31 08:01:59 simonb Exp $
# $NetBSD: Makefile,v 1.469 2008/07/31 08:28:17 simonb Exp $
# @(#)Makefile 8.1 (Berkeley) 6/18/93
MAN= aac.4 ac97.4 acardide.4 aceride.4 acphy.4 acpidalb.4 \
@ -54,8 +54,8 @@ MAN= aac.4 ac97.4 acardide.4 aceride.4 acphy.4 acpidalb.4 \
tp.4 tr.4 tra.4 trm.4 tty.4 tun.4 tqphy.4 twa.4 twe.4 txp.4 \
ubsec.4 udp.4 uep.4 ug.4 uha.4 uk.4 ukphy.4 unix.4 userconf.4 \
veriexec.4 vga.4 vge.4 viaide.4 vlan.4 vmmon.4 vmnet.4 vnd.4 vr.4 \
wd.4 wdc.4 wi.4 wm.4 wpi.4 wscons.4 wsdisplay.4 wsfont.4 wskbd.4 \
wsmouse.4 wsmux.4 \
wapbl.4 wd.4 wdc.4 wi.4 wm.4 wpi.4 wscons.4 wsdisplay.4 wsfont.4 \
wskbd.4 wsmouse.4 wsmux.4 \
xbox.4 xge.4 \
yds.4 ym.4 \
zero.4 zstty.4 zyd.4

187
share/man/man4/wapbl.4 Normal file
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.\" $NetBSD: wapbl.4,v 1.1 2008/07/31 08:28:17 simonb Exp $
.\"
.\" Copyright (c) 2008 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd July 21, 2008
.Dt WAPBL 4
.Os
.Sh NAME
.Nm WAPBL
.Nd Write Ahead Physical Block Logging file system journalling
.Sh SYNOPSIS
.Cd options WAPBL
.Cd options WAPBL_DEBUG
.Cd options WAPBL_DEBUG_SERIALIZE
.Sh DESCRIPTION
The
.Nm
driver provides meta-data journalling for file systems. In
particular, it is used with the fast file system (FFS) to provide
rapid file system consistency checking after a system outage.
It also provides better general-use performance over regular FFS.
.Pp
WAPBL currently maintains its journal in one of two locations:
.Bl -tag -width indent
.It - After the file system
The journal is placed in the same partition as the file system, but
between the filesystem and the end of the partition.
.It - Within the file system
The journal is allocated as a special contiguous file within the
filesystem.
The journal file is not visible via normal file system access.
.El
.Pp
A new journal is created automatically when a file system is mounted
via
.Xr mount 8
with the
.Pa -o log
option.
If no journal size has been specified with
.Xr tunefs 8 ,
then the size of the journal
will be based on 1MB of journal per 1GB of file system, to a maximum
journal size of 64MB.
.Pp
If there is adequate space between the end of the the file system and
the end of the partition, then unless the journal size has been
specified with
.Xr tunefs 8
then the journal will be created after the file system.
To obtain space between the file system and the end of the partition
the size of the partition can be adjusted using
.Xr disklabel 8 .
Care must be taken not to damage existing data on existing partitions,
but this method will work well if, for example, a swap partition can
be shrunk in order to accommodate the journal after the file system on
a partition before the swap partition.
.Pp
For a new file system,
.Bd -literal -offset indent
newfs -s -64m /dev/rwd0a
.Ed
.Pp
can be used to leave space for a 64MB journal at the end of
.Pa /dev/rwd0a .
.Pp
To specify the size of the journal within the file system
.Xr tunefs 8
can be used as follows:
.Bd -literal -offset indent
tunefs -l 64m /dev/rwd0a
.Ed
.Pp
to indicate that a journal of size 64MB on the file system on
.Pa /dev/rwd0a
should be created the next time that file system is mounted.
This must be done before the file system is mounted with the
.Dq -o log
option.
For existing file systems and general use, however, simply using
.Bd -literal -offset indent
mount -o log /dev/rwd0a /mnt
.Ed
.Pp
will be sufficient to create an appropriate journal within the file
system.
Running
.Bd -literal -offset indent
tunefs -l 0 /dev/rwd0a
.Ed
.Pp
will schedule the log for removal on the next read-write mount, and
running
.Bd -literal -offset indent
tunefs -l 0 /dev/rwd0a
.Ed
.Pp
followed by
.Bd -literal -offset indent
mount -o log /dev/rwd0a /mnt
.Ed
.Pp
will remove the log and then re-create it with the default size.
This method can also be used to grow or shrink the size of the journal.
.Pp
With the journal,
.Xr fsck 8
is no longer required at system boot.
If the system has been shutdown in an unclean fashion then the journal
will be replayed when the file system is mounted.
.Xr fsck 8
can still be used to force a consistency check of the file system
should that be desired.
.Xr WAPBL 8
has a number of debugging options.
The option
.Bd -unfilled -offset indent
options WAPBL_DEBUG
.Ed
.Pp
turns on general debugging.
The option
.Bd -unfilled -offset indent
options WAPBL_DEBUG_SERIALIZE
.Ed
.Pp
forces the serialization of all IO.
This is currently be used to help alleviate a performance issue
seen on multi-core machines, where multiple simultaneous extractions
of tar-files can cause degenerate performance.
.Pp
.Sh SEE ALSO
.Xr config 1 ,
.Xr fsck 8 ,
.Xr newfs 8 ,
.Xr mount 8 ,
.Xr umount 8
.Sh CAVEATS
.Xr fsync 2
causes the journal to be committed to disk, resulting in
non-negligible performance issues.
.Pp
There are also some pending issues with multiple simultaneous tar-file
extractions resulting in degenerate file system behavior.
The current work-around is to use
.Bd -unfilled -offset indent
options WAPBL_DEBUG_SERIALIZE
.Ed
.Pp
as mentioned above.
.Pp
In-file system log allocation should be done on a relatively quiet
file system. The error path for the log allocation could result in a
.Dq dangling inode
issue.
.Pp
If the file system is full then making a journal can fail.
.Sh HISTORY
.Nm
was originally written by Darrin B. Jewell while at Wasabi Systems
Inc.
Wasabi Systems contributed the code to
.Nx
and it first appeared in
.Nx 5.0 .