| 1 | '\" t
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| 2 | .\" Title: vfs_preopen
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| 3 | .\" Author: [see the "AUTHOR" section]
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| 4 | .\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
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| 5 | .\" Date: 02/19/2010
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| 6 | .\" Manual: System Administration tools
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| 7 | .\" Source: Samba 3.5
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| 8 | .\" Language: English
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| 9 | .\"
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| 10 | .TH "VFS_PREOPEN" "8" "02/19/2010" "Samba 3\&.5" "System Administration tools"
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| 11 | .\" -----------------------------------------------------------------
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| 12 | .\" * set default formatting
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| 13 | .\" -----------------------------------------------------------------
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| 14 | .\" disable hyphenation
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| 15 | .nh
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| 17 | .ad l
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| 18 | .\" -----------------------------------------------------------------
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| 19 | .\" * MAIN CONTENT STARTS HERE *
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| 20 | .\" -----------------------------------------------------------------
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| 21 | .SH "NAME"
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| 22 | vfs_preopen \- Hide read latencies for applications reading numbered files
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| 23 | .SH "SYNOPSIS"
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| 24 | .HP \w'\ 'u
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| 25 | vfs objects = preopen
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| 26 | .SH "DESCRIPTION"
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| 27 | .PP
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| 28 | This VFS module is part of the
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| 29 | \fBsamba\fR(7)
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| 30 | suite\&.
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| 31 | .PP
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| 32 | This module assists applications that want to read numbered files in sequence with very strict latency requirements\&. One area where this happens in video streaming applications that want to read one file per frame\&.
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| 33 | .PP
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| 34 | When you use this module, a number of helper processes is started that speculatively open files and read a number of bytes to prime the file system cache, so that later on when the real application\'s request comes along, no disk access is necessary\&.
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| 35 | .PP
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| 36 | This module is stackable\&.
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| 37 | .SH "OPTIONS"
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| 38 | .PP
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| 39 | preopen:names = /pattern/
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| 40 | .RS 4
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| 41 | preopen:names specifies the file name pattern which should trigger the preopen helpers to do their work\&. We assume that the files are numbered incrementally\&. So if your file names are numbered FRAME00000\&.frm FRAME00001\&.frm and so on you would list them as
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| 42 | preopen:names=/FRAME*\&.frm/
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| 43 | .RE
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| 44 | .PP
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| 45 | preopen:num_bytes = BYTES
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| 46 | .RS 4
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| 47 | Specifies the number of bytes the helpers should speculatively read, defaults to 1\&.
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| 48 | .RE
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| 49 | .PP
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| 50 | preopen:helpers = NUM\-PROCS
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| 51 | .RS 4
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| 52 | Number of forked helper processes, defaults to 1\&.
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| 53 | .RE
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| 54 | .PP
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| 55 | preopen:queuelen = NUM\-FILES
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| 56 | .RS 4
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| 57 | Number of files that should be speculatively opened\&. Defaults to the 10 subsequent files\&.
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| 58 | .RE
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| 59 | .SH "VERSION"
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| 60 | .PP
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| 61 | This man page is correct for version 3\&.3 of the Samba suite\&.
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| 62 | .SH "AUTHOR"
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| 63 | .PP
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| 64 | The original Samba software and related utilities were created by Andrew Tridgell\&. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed\&.
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| 65 | .PP
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| 66 | The PREOPEN VFS module was created with contributions from Volker Lendecke and the developers at IBM\&.
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