Update a bit.
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@ -1,4 +1,4 @@
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.\" $NetBSD: wapbl.4,v 1.2 2008/07/31 12:30:15 simonb Exp $
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.\" $NetBSD: wapbl.4,v 1.3 2008/07/31 14:14:07 simonb Exp $
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.\"
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.\" Copyright (c) 2008 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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@ -133,6 +133,7 @@ will be replayed when the file system is mounted.
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.Xr fsck 8
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can still be used to force a consistency check of the file system
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should that be desired.
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.Pp
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.Xr WAPBL 8
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has a number of debugging options.
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The option
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@ -158,12 +159,29 @@ of tar-files can cause degenerate performance.
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.Xr mount 8 ,
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.Xr umount 8
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.Sh CAVEATS
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An unreplayed
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.Nm
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journal (eg after a crash or power failure) may cause problems if the
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file system is then used with an older kernel or userland what isn't
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.Nm
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aware.
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.Pp
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.Xr fsync 2
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causes the journal to be committed to disk, resulting in
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non-negligible performance issues.
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This can have an impact on database software and other software
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that calls
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.Xr fsync 2
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often.
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.Pp
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There are also some pending issues with multiple simultaneous tar-file
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extractions resulting in degenerate file system behavior.
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File system snapshots
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.Xr ( fss 4 )
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currently do not work with
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.Nm .
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.Pp
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There are some pending issues with high metadata-rate workloads (like
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multiple simultaneous tar-file extractions) resulting in degenerate file
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system performance.
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The current work-around is to use
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.Bd -unfilled -offset indent
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options WAPBL_DEBUG_SERIALIZE
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@ -172,16 +190,22 @@ options WAPBL_DEBUG_SERIALIZE
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as mentioned above.
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.Pp
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In-file system log allocation should be done on a relatively quiet
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file system. The error path for the log allocation could result in a
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file system. The error path for log allocation failures could result
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in a
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.Dq dangling inode
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issue.
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issue, requiring an
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.Xr fsck 8
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to fix.
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.Pp
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If the file system is full then making a journal can fail.
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If the file system is full or close to full then making a journal can fail.
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.Sh HISTORY
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.Nm
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was originally written by Darrin B. Jewell while at Wasabi Systems
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Inc.
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was originally written by Darrin B. Jewell while at Wasabi Systems Inc.
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Wasabi Systems contributed the code to
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.Nx
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and it first appeared in
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and was integrated by Simon Burge, Antti Kantee, Andy Doran, and
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Greg Oster.
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.Pp
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.Nm
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first appeared in
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.Nx 5.0 .
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