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diff --git a/share/doc/smm/05.fastfs/1.t b/share/doc/smm/05.fastfs/1.t new file mode 100644 index 00000000000..dbdafc4e758 --- /dev/null +++ b/share/doc/smm/05.fastfs/1.t @@ -0,0 +1,112 @@ +.\" Copyright (c) 1986, 1993 +.\" The Regents of the University of California. 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. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. +.\" +.\" @(#)1.t 8.1 (Berkeley) 6/8/93 +.\" +.ds RH Introduction +.NH +Introduction +.PP +This paper describes the changes from the original 512 byte UNIX file +system to the new one released with the 4.2 Berkeley Software Distribution. +It presents the motivations for the changes, +the methods used to effect these changes, +the rationale behind the design decisions, +and a description of the new implementation. +This discussion is followed by a summary of +the results that have been obtained, +directions for future work, +and the additions and changes +that have been made to the facilities that are +available to programmers. +.PP +The original UNIX system that runs on the PDP-11\(dg +.FS +\(dg DEC, PDP, VAX, MASSBUS, and UNIBUS are +trademarks of Digital Equipment Corporation. +.FE +has simple and elegant file system facilities. File system input/output +is buffered by the kernel; +there are no alignment constraints on +data transfers and all operations are made to appear synchronous. +All transfers to the disk are in 512 byte blocks, which can be placed +arbitrarily within the data area of the file system. Virtually +no constraints other than available disk space are placed on file growth +[Ritchie74], [Thompson78].* +.FS +* In practice, a file's size is constrained to be less than about +one gigabyte. +.FE +.PP +When used on the VAX-11 together with other UNIX enhancements, +the original 512 byte UNIX file +system is incapable of providing the data throughput rates +that many applications require. +For example, +applications +such as VLSI design and image processing +do a small amount of processing +on a large quantities of data and +need to have a high throughput from the file system. +High throughput rates are also needed by programs +that map files from the file system into large virtual +address spaces. +Paging data in and out of the file system is likely +to occur frequently [Ferrin82b]. +This requires a file system providing +higher bandwidth than the original 512 byte UNIX +one that provides only about +two percent of the maximum disk bandwidth or about +20 kilobytes per second per arm [White80], [Smith81b]. +.PP +Modifications have been made to the UNIX file system to improve +its performance. +Since the UNIX file system interface +is well understood and not inherently slow, +this development retained the abstraction and simply changed +the underlying implementation to increase its throughput. +Consequently, users of the system have not been faced with +massive software conversion. +.PP +Problems with file system performance have been dealt with +extensively in the literature; see [Smith81a] for a survey. +Previous work to improve the UNIX file system performance has been +done by [Ferrin82a]. +The UNIX operating system drew many of its ideas from Multics, +a large, high performance operating system [Feiertag71]. +Other work includes Hydra [Almes78], +Spice [Thompson80], +and a file system for a LISP environment [Symbolics81]. +A good introduction to the physical latencies of disks is +described in [Pechura83]. +.ds RH Old file system +.sp 2 +.ne 1i |