Module Name: src
Committed By: ad
Date: Fri Apr 10 21:30:24 UTC 2009
Modified Files:
src/share/man/man4: wapbl.4
Log Message:
Sync with reality and be a bit less literal.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/share/man/man4/wapbl.4
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man4/wapbl.4
diff -u src/share/man/man4/wapbl.4:1.8 src/share/man/man4/wapbl.4:1.9
--- src/share/man/man4/wapbl.4:1.8 Thu Feb 26 07:21:06 2009
+++ src/share/man/man4/wapbl.4 Fri Apr 10 21:30:24 2009
@@ -1,6 +1,6 @@
-.\" $NetBSD: wapbl.4,v 1.8 2009/02/26 07:21:06 wiz Exp $
+.\" $NetBSD: wapbl.4,v 1.9 2009/04/10 21:30:24 ad Exp $
.\"
-.\" Copyright (c) 2008 The NetBSD Foundation, Inc.
+.\" Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
@@ -24,7 +24,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.Dd February 25, 2009
+.Dd April 10, 2009
.Dt WAPBL 4
.Os
.Sh NAME
@@ -33,7 +33,6 @@
.Sh SYNOPSIS
.Cd options WAPBL
.Cd options WAPBL_DEBUG
-.Cd options WAPBL_DEBUG_SERIALIZE
.Sh DESCRIPTION
The
.Nm
@@ -134,17 +133,9 @@
can still be used to force a consistency check of the file system
should that be desired.
.Pp
-.Nm
-has a number of debugging options.
-The option
+For kernel developers, the compile time option
.Dv WAPBL_DEBUG
-turns on general debugging.
-The option
-.Dv WAPBL_DEBUG_SERIALIZE
-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.
+turns on debugging.
.Sh SEE ALSO
.Xr config 1 ,
.Xr fsck 8 ,
@@ -170,18 +161,17 @@
first appeared in
.Nx 5.0 .
.Sh CAVEATS
-An unreplayed
-.Nm
-journal (eg after a crash or power failure) may cause problems if the
-file system is then used with an older kernel or userland what isn't
+Older releases of the system, and other systems that support the
+.Dv UFS
+format should only access
.Nm
-aware.
-.Pp
-An older
+file systems in read-only mode.
+Additionally, the
.Xr fsck 8
-that isn't
+command from such systems should not be run against
.Nm
-aware will not be able to deal with an in-filesystem log.
+file systems.
+Failure to observe these guidelines may damage the file system.
.Pp
.Nm
requires the super block to be in the UFS2 format.
@@ -196,8 +186,8 @@
.Xr fsck_ffs 8 .
.Pp
.Xr fsync 2
-causes the journal to be committed to disk, resulting in
-non-negligible performance issues.
+causes all outstanding metadata transactions to be committed to disk,
+introducing additional latency.
This can have an impact on database software and other software
that calls
.Xr fsync 2
@@ -205,16 +195,9 @@
.Pp
File system snapshots
.Pq Xr fss 4
-currently do not work with
+and quotas do not yet work with
.Nm .
.Pp
-There are some pending issues with high metadata-rate workloads (like
-multiple simultaneous tar-file extractions) resulting in degenerate file
-system performance.
-The current work-around is to use the
-.Dv WAPBL_DEBUG_SERIALIZE
-option, as mentioned above.
-.Pp
In-file system log allocation should be done on a relatively quiet
file system.
The error path for log allocation failures could result in a
@@ -222,5 +205,3 @@
issue, requiring an
.Xr fsck 8
to fix.
-.Pp
-If the file system is full or close to full then making a journal can fail.
