.\" $OpenBSD: ffs_softupdates.4,v 1.3 2000/02/16 16:53:23 aaron Exp $ .\" .\" Copyright (c) 1998 Todd C. Miller .\" 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. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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 March 15, 1998 .Dt FFS_SOFTUPDATES 4 .Os .Sh NAME .Nm ffs_softupdates .Nd asynchronous file system writes .Sh DESCRIPTION The .Nm FFS_SOFTUPDATES kernel config option enables a scheme that uses partial ordering of buffer cache operations to allow metadata updates in the fast filesystem to happen asynchronously, increasing write performance significantly. Normally, the .Em ffs filesystem writes metadata updates synchronously which exacts a performance penalty in favor of filesystem integrity. With .Em soft updates , you gain the performance of asynchronous writes while retaining the safety of synchronous metadata updates. .Pp .Em Soft Updates must be enabled on a per-filesystem basis. To do this, boot into single user mode and run .Dq tunefs -s enable special on each character special disk device you want to enable .Em soft updates on, then run .Dq reboot -n . .Sh CAVEATS Soft updates should be considered experimental at this time. .br There should be a .Xr mount 2 option to enable .Em soft updates . .br The current license for .Nm is more restrictive than the rest of the .Ox kernel; this will be changed at a future date. .Sh AUTHOR Marshall Kirk McKusick .Sh LICENSE The following are the copyrights and redistribution conditions that apply to this copy of the soft update software. For a license to use, redistribute or sell the soft update software under conditions other than those described here, please contact the author at one of the following addresses: .Bd -literal -offset indent Marshall Kirk McKusick mckusick@mckusick.com 1614 Oxford Street +1-510-843-9542 Berkeley, CA 94709-1608 USA .Ed .Pp Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: .Bl -tag -width XXX .It 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. .It 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. .It 3. None of the names of McKusick, Ganger, Patt, or the University of Michigan may be used to endorse or promote products derived from this software without specific prior written permission. .It 4. Redistributions in any form must be accompanied by information on how to obtain complete source code for any accompanying software that uses this software. This source code must either be included in the distribution or be available for no more than the cost of distribution plus a nominal fee, and must be freely redistributable under reasonable conditions. For an executable file, complete source code means the source code for all modules it contains. It does not mean source code for modules or files that typically accompany the operating system on which the executable file runs, e.g., standard library modules or system header files. .El .Pp THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``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 MARSHALL KIRK MCKUSICK 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. .Sh SEE ALSO .Xr fs 5 , .Xr config 8 , .Xr sysctl 8 , .Xr tunefs 8 . .Rs .%T "A Fast Filesystem for UNIX" .%A Marshall Kirk McKusick .%A William N. Joy .%A Samuel J. Leffler .%A Robert S. Fabry .%C Computer Science Research Group .Re .Pp .Rs .%T "Soft Updates: A Solution to the Metadata Update Problem in File Systems" .%A Gregory R. Ganger .%A Yale N. Patt .%R CSE-TR-254-95 .%C "University of Michigan, Ann Arbor" .Re .br .Li http://www.ece.cmu.edu/~ganger/papers/CSE-TR-254-95/