diff --git a/share/man/man4/wapbl.4 b/share/man/man4/wapbl.4 index 801e7058952a..c32042b52ab0 100644 --- a/share/man/man4/wapbl.4 +++ b/share/man/man4/wapbl.4 @@ -1,4 +1,4 @@ -.\" $NetBSD: wapbl.4,v 1.2 2008/07/31 12:30:15 simonb Exp $ +.\" $NetBSD: wapbl.4,v 1.3 2008/07/31 14:14:07 simonb Exp $ .\" .\" Copyright (c) 2008 The NetBSD Foundation, Inc. .\" All rights reserved. @@ -46,10 +46,10 @@ 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. +between the file system and the end of the partition. .It - Within the file system The journal is allocated as a special contiguous file within the -filesystem. +file system. The journal file is not visible via normal file system access. .El .Pp @@ -133,6 +133,7 @@ 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. +.Pp .Xr WAPBL 8 has a number of debugging options. The option @@ -158,12 +159,29 @@ of tar-files can cause degenerate performance. .Xr mount 8 , .Xr umount 8 .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 +.Nm +aware. +.Pp .Xr fsync 2 causes the journal to be committed to disk, resulting in non-negligible performance issues. +This can have an impact on database software and other software +that calls +.Xr fsync 2 +often. .Pp -There are also some pending issues with multiple simultaneous tar-file -extractions resulting in degenerate file system behavior. +File system snapshots +.Xr ( fss 4 ) +currently do not 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 .Bd -unfilled -offset indent options WAPBL_DEBUG_SERIALIZE @@ -172,16 +190,22 @@ options WAPBL_DEBUG_SERIALIZE 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 +file system. The error path for log allocation failures could result +in a .Dq dangling inode -issue. +issue, requiring an +.Xr fsck 8 +to fix. .Pp -If the file system is full then making a journal can fail. +If the file system is full or close to full then making a journal can fail. .Sh HISTORY .Nm -was originally written by Darrin B. Jewell while at Wasabi Systems -Inc. +was originally written by Darrin B. Jewell while at Wasabi Systems Inc. Wasabi Systems contributed the code to .Nx -and it first appeared in +and was integrated by Simon Burge, Antti Kantee, Andy Doran, and +Greg Oster. +.Pp +.Nm +first appeared in .Nx 5.0 .