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r231 r272 1 <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 17. File and Record Locking</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="The Official Samba 3.2.x HOWTO and Reference Guide"><link rel="up" href="optional.html" title="Part III. Advanced Configuration"><link rel="prev" href="AccessControls.html" title="Chapter 16. File, Directory, and Share Access Controls"><link rel="next" href="securing-samba.html" title="Chapter 18. Securing Samba"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 17. File and Record Locking</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="AccessControls.html">Prev</a> </td><th width="60%" align="center">Part III. Advanced Configuration</th><td width="20%" align="right"> <a accesskey="n" href="securing-samba.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="locking"></a>Chapter 17. File and Record Locking</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Jeremy</span> <span class="orgname">Samba Team</span> <span class="surname">Allison</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jra@samba.org">jra@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jelmer</span> <span class="othername">R.</span> <span class="orgname">The Samba Team</span> <span class="surname">Vernooij</span></h3><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jelmer@samba.org">jelmer@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="orgname">Samba Team</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jht@samba.org">jht@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Eric</span> <span class="orgname">HP Oplocks Usage Recommendations Whitepaper</span> <span class="surname">Roseme</span></h3><div class="affiliation"><span class="orgname">HP Oplocks Usage Recommendations Whitepaper<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:eric.roseme@hp.com">eric.roseme@hp.com</a>></code></p></div></div></div></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="locking.html#id26155 35">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="locking.html#id2615632">Discussion</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2615890">Opportunistic Locking Overview</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2616885">Samba Oplocks Control</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2616979">Example Configuration</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617393">MS Windows Oplocks and Caching Controls</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2617580">Workstation Service Entries</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617602">Server Service Entries</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617668">Persistent Data Corruption</a></span></dt><dt><span class="sect1"><a href="locking.html#id2617693">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2617761">locking.tdb Error Messages</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617791">Problems Saving Files in MS Office on Windows XP</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617816">Long Delays Deleting Files over Network with XP SP1</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617847">Additional Reading</a></span></dt></dl></div><p>2 <a class="indexterm" name="id26155 24"></a>1 <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 17. File and Record Locking</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="The Official Samba 3.2.x HOWTO and Reference Guide"><link rel="up" href="optional.html" title="Part III. Advanced Configuration"><link rel="prev" href="AccessControls.html" title="Chapter 16. File, Directory, and Share Access Controls"><link rel="next" href="securing-samba.html" title="Chapter 18. Securing Samba"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 17. File and Record Locking</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="AccessControls.html">Prev</a> </td><th width="60%" align="center">Part III. Advanced Configuration</th><td width="20%" align="right"> <a accesskey="n" href="securing-samba.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="locking"></a>Chapter 17. File and Record Locking</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Jeremy</span> <span class="orgname">Samba Team</span> <span class="surname">Allison</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jra@samba.org">jra@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jelmer</span> <span class="othername">R.</span> <span class="orgname">The Samba Team</span> <span class="surname">Vernooij</span></h3><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jelmer@samba.org">jelmer@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="orgname">Samba Team</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jht@samba.org">jht@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Eric</span> <span class="orgname">HP Oplocks Usage Recommendations Whitepaper</span> <span class="surname">Roseme</span></h3><div class="affiliation"><span class="orgname">HP Oplocks Usage Recommendations Whitepaper<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:eric.roseme@hp.com">eric.roseme@hp.com</a>></code></p></div></div></div></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="locking.html#id2615585">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="locking.html#id2615682">Discussion</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2615940">Opportunistic Locking Overview</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2616938">Samba Oplocks Control</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2617033">Example Configuration</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617446">MS Windows Oplocks and Caching Controls</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2617633">Workstation Service Entries</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617655">Server Service Entries</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617721">Persistent Data Corruption</a></span></dt><dt><span class="sect1"><a href="locking.html#id2617747">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="locking.html#id2617814">locking.tdb Error Messages</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617844">Problems Saving Files in MS Office on Windows XP</a></span></dt><dt><span class="sect2"><a href="locking.html#id2617869">Long Delays Deleting Files over Network with XP SP1</a></span></dt></dl></dd><dt><span class="sect1"><a href="locking.html#id2617901">Additional Reading</a></span></dt></dl></div><p> 2 <a class="indexterm" name="id2615574"></a> 3 3 One area that causes trouble for many network administrators is locking. 4 4 The extent of the problem is readily evident from searches over the Internet. 5 </p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id26155 35"></a>Features and Benefits</h2></div></div></div><p>6 <a class="indexterm" name="id26155 43"></a>5 </p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2615585"></a>Features and Benefits</h2></div></div></div><p> 6 <a class="indexterm" name="id2615593"></a> 7 7 Samba provides all the same locking semantics that MS Windows clients expect 8 8 and that MS Windows NT4/200x servers also provide. 9 9 </p><p> 10 <a class="indexterm" name="id2615 555"></a>10 <a class="indexterm" name="id2615605"></a> 11 11 The term <span class="emphasis"><em>locking</em></span> has exceptionally broad meaning and covers 12 12 a range of functions that are all categorized under this one term. 13 13 </p><p> 14 <a class="indexterm" name="id2615 571"></a>15 <a class="indexterm" name="id2615 578"></a>16 <a class="indexterm" name="id2615 585"></a>14 <a class="indexterm" name="id2615621"></a> 15 <a class="indexterm" name="id2615628"></a> 16 <a class="indexterm" name="id2615635"></a> 17 17 Opportunistic locking is a desirable feature when it can enhance the 18 18 perceived performance of applications on a networked client. However, the … … 24 24 it is intended to provide. 25 25 </p><p> 26 <a class="indexterm" name="id26156 04"></a>26 <a class="indexterm" name="id2615654"></a> 27 27 The MS Windows network administrator needs to be aware that file and record 28 28 locking semantics (behavior) can be controlled either in Samba or by way of registry 29 29 settings on the MS Windows client. 30 30 </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> 31 <a class="indexterm" name="id26156 19"></a>31 <a class="indexterm" name="id2615670"></a> 32 32 Sometimes it is necessary to disable locking control settings on the Samba 33 33 server as well as on each MS Windows client! 34 </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id26156 32"></a>Discussion</h2></div></div></div><p>35 <a class="indexterm" name="id26156 39"></a>36 <a class="indexterm" name="id26156 46"></a>34 </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2615682"></a>Discussion</h2></div></div></div><p> 35 <a class="indexterm" name="id2615690"></a> 36 <a class="indexterm" name="id2615696"></a> 37 37 There are two types of locking that need to be performed by an SMB server. 38 38 The first is <span class="emphasis"><em>record locking</em></span> that allows a client to lock … … 40 40 that are specified when a file is open. 41 41 </p><p> 42 <a class="indexterm" name="id2615 667"></a>43 <a class="indexterm" name="id2615 674"></a>44 <a class="indexterm" name="id2615 681"></a>45 <a class="indexterm" name="id2615 688"></a>46 <a class="indexterm" name="id2615 695"></a>42 <a class="indexterm" name="id2615717"></a> 43 <a class="indexterm" name="id2615724"></a> 44 <a class="indexterm" name="id2615731"></a> 45 <a class="indexterm" name="id2615738"></a> 46 <a class="indexterm" name="id2615745"></a> 47 47 Record locking semantics under UNIX are very different from record locking under 48 48 Windows. Versions of Samba before 2.2 have tried to use the native fcntl() UNIX … … 54 54 many more differences, too many to be listed here. 55 55 </p><p> 56 <a class="indexterm" name="id26157 15"></a>57 <a class="indexterm" name="id26157 22"></a>56 <a class="indexterm" name="id2615765"></a> 57 <a class="indexterm" name="id2615772"></a> 58 58 Samba 2.2 and above implement record locking completely independently of the 59 59 underlying UNIX system. If a byte-range lock that the client requests happens … … 61 61 No other locks can be seen by UNIX, anyway. 62 62 </p><p> 63 <a class="indexterm" name="id26157 37"></a>64 <a class="indexterm" name="id26157 44"></a>63 <a class="indexterm" name="id2615787"></a> 64 <a class="indexterm" name="id2615794"></a> 65 65 Strictly speaking, an SMB server should check for locks before every read and write call on 66 66 a file. Unfortunately, with the way fcntl() works, this can be slow and may overstress … … 71 71 will make lock checking calls on <span class="emphasis"><em>every</em></span> read and write call. 72 72 </p><p> 73 <a class="indexterm" name="id2615 785"></a>73 <a class="indexterm" name="id2615836"></a> 74 74 You can also disable byte-range locking completely by using 75 75 <a class="link" href="smb.conf.5.html#LOCKING" target="_top">locking = no</a>. … … 78 78 tell clients that everything is okay. 79 79 </p><p> 80 <a class="indexterm" name="id26158 13"></a>81 <a class="indexterm" name="id26158 19"></a>82 <a class="indexterm" name="id26158 26"></a>83 <a class="indexterm" name="id26158 33"></a>84 <a class="indexterm" name="id26158 39"></a>85 <a class="indexterm" name="id26158 46"></a>86 <a class="indexterm" name="id2615 852"></a>80 <a class="indexterm" name="id2615863"></a> 81 <a class="indexterm" name="id2615869"></a> 82 <a class="indexterm" name="id2615876"></a> 83 <a class="indexterm" name="id2615883"></a> 84 <a class="indexterm" name="id2615890"></a> 85 <a class="indexterm" name="id2615896"></a> 86 <a class="indexterm" name="id2615903"></a> 87 87 The second class of locking is the <span class="emphasis"><em>deny modes</em></span>. These 88 88 are set by an application when it opens a file to determine what types of … … 91 91 <code class="constant">DENY_WRITE</code>, or <code class="constant">DENY_ALL</code>. There are also special compatibility 92 92 modes called <code class="constant">DENY_FCB</code> and <code class="constant">DENY_DOS</code>. 93 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2615 890"></a>Opportunistic Locking Overview</h3></div></div></div><p>94 <a class="indexterm" name="id2615 898"></a>95 <a class="indexterm" name="id26159 05"></a>96 <a class="indexterm" name="id26159 12"></a>93 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2615940"></a>Opportunistic Locking Overview</h3></div></div></div><p> 94 <a class="indexterm" name="id2615948"></a> 95 <a class="indexterm" name="id2615955"></a> 96 <a class="indexterm" name="id2615962"></a> 97 97 Opportunistic locking (oplocks) is invoked by the Windows file system 98 98 (as opposed to an API) via registry entries (on the server and the client) … … 101 101 locally on the client that allows the following: 102 102 </p><div class="variablelist"><dl><dt><span class="term">Read-ahead:</span></dt><dd><p> 103 <a class="indexterm" name="id26159 35"></a>103 <a class="indexterm" name="id2615986"></a> 104 104 The client reads the local copy of the file, eliminating network latency. 105 105 </p></dd><dt><span class="term">Write caching:</span></dt><dd><p> 106 <a class="indexterm" name="id261 5954"></a>106 <a class="indexterm" name="id2616004"></a> 107 107 The client writes to the local copy of the file, eliminating network latency. 108 108 </p></dd><dt><span class="term">Lock caching:</span></dt><dd><p> 109 <a class="indexterm" name="id261 5972"></a>109 <a class="indexterm" name="id2616022"></a> 110 110 The client caches application locks locally, eliminating network latency. 111 111 </p></dd></dl></div><p> 112 <a class="indexterm" name="id261 5986"></a>113 <a class="indexterm" name="id261 5993"></a>114 <a class="indexterm" name="id26160 00"></a>112 <a class="indexterm" name="id2616036"></a> 113 <a class="indexterm" name="id2616043"></a> 114 <a class="indexterm" name="id2616050"></a> 115 115 The performance enhancement of oplocks is due to the opportunity of 116 116 exclusive access to the file even if it is opened with deny-none … … 118 118 other processes. 119 119 </p><div class="variablelist"><p class="title"><b>Windows Defines Four Kinds of Oplocks:</b></p><dl><dt><span class="term">Level1 Oplock</span></dt><dd><p> 120 <a class="indexterm" name="id26160 31"></a>121 <a class="indexterm" name="id26160 37"></a>122 <a class="indexterm" name="id26160 44"></a>123 <a class="indexterm" name="id2616 051"></a>120 <a class="indexterm" name="id2616081"></a> 121 <a class="indexterm" name="id2616088"></a> 122 <a class="indexterm" name="id2616094"></a> 123 <a class="indexterm" name="id2616101"></a> 124 124 The redirector sees that the file was opened with deny 125 125 none (allowing concurrent access), verifies that no … … 129 129 operations on the cached local file. 130 130 </p><p> 131 <a class="indexterm" name="id2616 067"></a>132 <a class="indexterm" name="id2616 074"></a>133 <a class="indexterm" name="id2616 081"></a>134 <a class="indexterm" name="id2616 088"></a>131 <a class="indexterm" name="id2616117"></a> 132 <a class="indexterm" name="id2616124"></a> 133 <a class="indexterm" name="id2616131"></a> 134 <a class="indexterm" name="id2616138"></a> 135 135 If a second process attempts to open the file, the open 136 136 is deferred while the redirector "breaks" the original … … 146 146 the oplock break. 147 147 </p></dd><dt><span class="term">Level2 Oplock</span></dt><dd><p> 148 <a class="indexterm" name="id26161 26"></a>149 <a class="indexterm" name="id26161 33"></a>150 <a class="indexterm" name="id26161 40"></a>148 <a class="indexterm" name="id2616177"></a> 149 <a class="indexterm" name="id2616184"></a> 150 <a class="indexterm" name="id2616190"></a> 151 151 Performs like a Level1 oplock, except caching is only 152 152 operative for reads. All other operations are performed 153 153 on the server disk copy of the file. 154 154 </p></dd><dt><span class="term">Filter Oplock</span></dt><dd><p> 155 <a class="indexterm" name="id2616 160"></a>155 <a class="indexterm" name="id2616211"></a> 156 156 Does not allow write or delete file access. 157 157 </p></dd><dt><span class="term">Batch Oplock</span></dt><dd><p> 158 <a class="indexterm" name="id2616 179"></a>158 <a class="indexterm" name="id2616229"></a> 159 159 Manipulates file openings and closings and allows caching 160 160 of file attributes. 161 161 </p></dd></dl></div><p> 162 <a class="indexterm" name="id2616 193"></a>162 <a class="indexterm" name="id2616243"></a> 163 163 An important detail is that oplocks are invoked by the file system, not 164 164 an application API. Therefore, an application can close an oplocked … … 167 167 preparation for the subsequent open by the second process. 168 168 </p><p> 169 <a class="indexterm" name="id26162 09"></a>170 <a class="indexterm" name="id26162 16"></a>171 <a class="indexterm" name="id26162 23"></a>172 <a class="indexterm" name="id26162 30"></a>169 <a class="indexterm" name="id2616259"></a> 170 <a class="indexterm" name="id2616266"></a> 171 <a class="indexterm" name="id2616273"></a> 172 <a class="indexterm" name="id2616280"></a> 173 173 <span class="emphasis"><em>Opportunistic locking</em></span> is actually an improper name for this feature. 174 174 The true benefit of this feature is client-side data caching, and … … 180 180 client-side caching benefit is negated. 181 181 </p><p> 182 <a class="indexterm" name="id2616 252"></a>182 <a class="indexterm" name="id2616302"></a> 183 183 The actual decision that a user or administrator should consider is 184 184 whether it is sensible to share among multiple users data that will … … 190 190 unreliable, or counterproductive. 191 191 </p><p> 192 <a class="indexterm" name="id2616 277"></a>192 <a class="indexterm" name="id2616327"></a> 193 193 Oplocks is by default set to “<span class="quote">on</span>” by Samba on all 194 194 configured shares, so careful attention should be given to each case to … … 197 197 where oplocks may be effectively configured. 198 198 </p><p> 199 <a class="indexterm" name="id2616 295"></a>200 <a class="indexterm" name="id26163 02"></a>199 <a class="indexterm" name="id2616346"></a> 200 <a class="indexterm" name="id2616352"></a> 201 201 Windows oplocks is a lightweight performance-enhancing 202 202 feature. It is not a robust and reliable protocol. Every … … 209 209 storm. This configuration will likely encounter problems with oplocks. 210 210 </p><p> 211 <a class="indexterm" name="id26163 31"></a>211 <a class="indexterm" name="id2616372"></a> 212 212 Oplocks can be beneficial to perceived client performance when treated 213 213 as a configuration toggle for client-side data caching. If the data … … 223 223 continuous data availability. 224 224 </p><p> 225 <a class="indexterm" name="id26163 54"></a>226 <a class="indexterm" name="id2616 361"></a>225 <a class="indexterm" name="id2616395"></a> 226 <a class="indexterm" name="id2616402"></a> 227 227 Windows client failover behavior is more at risk of application 228 228 interruption than other platforms because it is dependent upon an … … 234 234 require restarting. 235 235 </p><p> 236 <a class="indexterm" name="id2616 388"></a>237 <a class="indexterm" name="id2616 394"></a>238 <a class="indexterm" name="id26164 01"></a>236 <a class="indexterm" name="id2616429"></a> 237 <a class="indexterm" name="id2616435"></a> 238 <a class="indexterm" name="id2616442"></a> 239 239 If a client session has been caching writes and reads locally due to 240 240 oplocks, it is likely that the data will be lost when the … … 251 251 testing should be done with all affected applications with oplocks 252 252 enabled and disabled. 253 </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26164 26"></a>Exclusively Accessed Shares</h4></div></div></div><p>253 </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616466"></a>Exclusively Accessed Shares</h4></div></div></div><p> 254 254 Oplocks is most effective when it is confined to shares 255 255 that are exclusively accessed by a single user, or by only one user at … … 260 260 Home directories are the most obvious examples of where the performance 261 261 benefit of oplocks can be safely realized. 262 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26164 46"></a>Multiple-Accessed Shares or Files</h4></div></div></div><p>262 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616487"></a>Multiple-Accessed Shares or Files</h4></div></div></div><p> 263 263 As each additional user accesses a file in a share with oplocks 264 264 enabled, the potential for delays and resulting perceived poor … … 272 272 the potential performance improvement is negated and eventually results 273 273 in a performance bottleneck. 274 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616 470"></a>UNIX or NFS Client-Accessed Files</h4></div></div></div><p>275 <a class="indexterm" name="id2616 478"></a>276 <a class="indexterm" name="id2616 485"></a>274 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616510"></a>UNIX or NFS Client-Accessed Files</h4></div></div></div><p> 275 <a class="indexterm" name="id2616519"></a> 276 <a class="indexterm" name="id2616525"></a> 277 277 Local UNIX and NFS clients access files without a mandatory 278 278 file-locking mechanism. Thus, these client platforms are incapable of … … 284 284 If files are shared between Windows clients and either local UNIX 285 285 or NFS users, turn oplocks off. 286 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26165 05"></a>Slow and/or Unreliable Networks</h4></div></div></div><p>287 <a class="indexterm" name="id26165 13"></a>288 <a class="indexterm" name="id26165 20"></a>289 <a class="indexterm" name="id26165 27"></a>286 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616546"></a>Slow and/or Unreliable Networks</h4></div></div></div><p> 287 <a class="indexterm" name="id2616554"></a> 288 <a class="indexterm" name="id2616561"></a> 289 <a class="indexterm" name="id2616568"></a> 290 290 The biggest potential performance improvement for oplocks 291 291 occurs when the client-side caching of reads and writes delivers the … … 302 302 oplocks if there is any chance of multiple users 303 303 regularly opening the same file. 304 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26165 53"></a>Multiuser Databases</h4></div></div></div><p>305 <a class="indexterm" name="id2616 561"></a>306 <a class="indexterm" name="id2616 568"></a>307 <a class="indexterm" name="id2616 575"></a>304 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616594"></a>Multiuser Databases</h4></div></div></div><p> 305 <a class="indexterm" name="id2616601"></a> 306 <a class="indexterm" name="id2616608"></a> 307 <a class="indexterm" name="id2616615"></a> 308 308 Multiuser databases clearly pose a risk due to their very nature they are typically heavily 309 309 accessed by numerous users at random intervals. Placing a multiuser database on a share with oplocks enabled 310 310 will likely result in a locking management bottleneck on the Samba server. Whether the database application is 311 311 developed in-house or a commercially available product, ensure that the share has oplocks disabled. 312 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616 594"></a>PDM Data Shares</h4></div></div></div><p>313 <a class="indexterm" name="id26166 01"></a>314 <a class="indexterm" name="id26166 08"></a>315 <a class="indexterm" name="id26166 15"></a>316 <a class="indexterm" name="id26166 22"></a>317 <a class="indexterm" name="id26166 29"></a>312 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616635"></a>PDM Data Shares</h4></div></div></div><p> 313 <a class="indexterm" name="id2616642"></a> 314 <a class="indexterm" name="id2616649"></a> 315 <a class="indexterm" name="id2616656"></a> 316 <a class="indexterm" name="id2616663"></a> 317 <a class="indexterm" name="id2616670"></a> 318 318 Process data management (PDM) applications such as IMAN, Enovia, and Clearcase are increasing in usage with 319 319 Windows client platforms and therefore with SMB datastores. PDM applications manage multiuser environments for … … 323 323 application and PDM server to negotiate and maintain. It is appropriate to eliminate the client OS from any 324 324 caching tasks, and the server from any oplocks management, by disabling oplocks on the share. 325 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616 651"></a>Beware of Force User</h4></div></div></div><p>326 <a class="indexterm" name="id2616 659"></a>325 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616704"></a>Beware of Force User</h4></div></div></div><p> 326 <a class="indexterm" name="id2616712"></a> 327 327 Samba includes an <code class="filename">smb.conf</code> parameter called <a class="link" href="smb.conf.5.html#FORCEUSER" target="_top">force user</a> that changes the user 328 328 accessing a share from the incoming user to whatever user is defined by the <code class="filename">smb.conf</code> variable. If oplocks is … … 339 339 </p></li><li><p> 340 340 Oplocks enabled. 341 </p></li></ul></div></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26167 39"></a>Advanced Samba Oplocks Parameters</h4></div></div></div><p>342 <a class="indexterm" name="id2616 747"></a>343 <a class="indexterm" name="id2616 754"></a>344 <a class="indexterm" name="id2616 761"></a>341 </p></li></ul></div></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616792"></a>Advanced Samba Oplocks Parameters</h4></div></div></div><p> 342 <a class="indexterm" name="id2616800"></a> 343 <a class="indexterm" name="id2616807"></a> 344 <a class="indexterm" name="id2616814"></a> 345 345 Samba provides oplock parameters that allow the 346 346 administrator to adjust various properties of the oplock mechanism to … … 351 351 <a class="link" href="smb.conf.5.html#OPLOCKCONTENTIONLIMIT" target="_top">oplock contention limit</a>. 352 352 </p><p> 353 <a class="indexterm" name="id26168 01"></a>353 <a class="indexterm" name="id2616854"></a> 354 354 For most users, administrators, and environments, if these parameters 355 355 are required, then the better option is simply to turn oplocks off. … … 357 357 this parameter unless you have read and understood the Samba oplock code.</span>” 358 358 This is good advice. 359 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id26168 18"></a>Mission-Critical, High-Availability</h4></div></div></div><p>359 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2616871"></a>Mission-Critical, High-Availability</h4></div></div></div><p> 360 360 In mission-critical, high-availability environments, data integrity is 361 361 often a priority. Complex and expensive configurations are implemented … … 387 387 testing should be done with all affected applications with oplocks 388 388 enabled and disabled. 389 </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2616 885"></a>Samba Oplocks Control</h2></div></div></div><p>389 </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2616938"></a>Samba Oplocks Control</h2></div></div></div><p> 390 390 Oplocks is a unique Windows file locking feature. It is 391 391 not really file locking, but is included in most discussions of Windows … … 437 437 Another factor to consider is the perceived performance of file access. If oplocks provide no 438 438 measurable speed benefit on your network, it might not be worth the hassle of dealing with them. 439 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id261 6979"></a>Example Configuration</h3></div></div></div><p>439 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617033"></a>Example Configuration</h3></div></div></div><p> 440 440 In the following section we examine two distinct aspects of Samba locking controls. 441 </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id261 6990"></a>Disabling Oplocks</h4></div></div></div><p>441 </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2617043"></a>Disabling Oplocks</h4></div></div></div><p> 442 442 You can disable oplocks on a per-share basis with the following: 443 443 </p><p> 444 </p><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[acctdata]</code></em></td></tr><tr><td><a class="indexterm" name="id26170 17"></a><em class="parameter"><code>oplocks = False</code></em></td></tr><tr><td><a class="indexterm" name="id2617028"></a><em class="parameter"><code>level2 oplocks = False</code></em></td></tr></table><p>444 </p><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[acctdata]</code></em></td></tr><tr><td><a class="indexterm" name="id2617070"></a><em class="parameter"><code>oplocks = False</code></em></td></tr><tr><td><a class="indexterm" name="id2617082"></a><em class="parameter"><code>level2 oplocks = False</code></em></td></tr></table><p> 445 445 </p><p> 446 446 The default oplock type is Level1. Level2 oplocks are enabled on a per-share basis … … 449 449 Alternately, you could disable oplocks on a per-file basis within the share: 450 450 </p><p> 451 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2617 064"></a><em class="parameter"><code>veto oplock files = /*.mdb/*.MDB/*.dbf/*.DBF/</code></em></td></tr></table><p>451 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2617118"></a><em class="parameter"><code>veto oplock files = /*.mdb/*.MDB/*.dbf/*.DBF/</code></em></td></tr></table><p> 452 452 </p><p> 453 453 If you are experiencing problems with oplocks, as apparent from Samba's log entries, 454 454 you may want to play it safe and disable oplocks and Level2 oplocks. 455 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2617 085"></a>Disabling Kernel Oplocks</h4></div></div></div><p>455 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2617138"></a>Disabling Kernel Oplocks</h4></div></div></div><p> 456 456 Kernel oplocks is an <code class="filename">smb.conf</code> parameter that notifies Samba (if 457 457 the UNIX kernel has the capability to send a Windows client an oplock … … 466 466 basis in the <code class="filename">smb.conf</code> file. 467 467 </p><p> 468 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id26171 25"></a><em class="parameter"><code>kernel oplocks = yes</code></em></td></tr></table><p>468 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2617178"></a><em class="parameter"><code>kernel oplocks = yes</code></em></td></tr></table><p> 469 469 The default is no. 470 470 </p><p> … … 481 481 <code class="filename">smb.conf</code> file as shown in <a class="link" href="locking.html#far1" title="Example 17.1. Share with Some Files Oplocked">“Share with Some Files Oplocked”</a>. 482 482 </p><p> 483 </p><div class="example"><a name="far1"></a><p class="title"><b>Example 17.1. Share with Some Files Oplocked</b></p><div class="example-contents"><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id26172 01"></a><em class="parameter"><code>veto oplock files = /filename.htm/*.txt/</code></em></td></tr><tr><td> </td></tr><tr><td><em class="parameter"><code>[share_name]</code></em></td></tr><tr><td><a class="indexterm" name="id2617222"></a><em class="parameter"><code>veto oplock files = /*.exe/filename.ext/</code></em></td></tr></table></div></div><p><br class="example-break">483 </p><div class="example"><a name="far1"></a><p class="title"><b>Example 17.1. Share with Some Files Oplocked</b></p><div class="example-contents"><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id2617254"></a><em class="parameter"><code>veto oplock files = /filename.htm/*.txt/</code></em></td></tr><tr><td> </td></tr><tr><td><em class="parameter"><code>[share_name]</code></em></td></tr><tr><td><a class="indexterm" name="id2617276"></a><em class="parameter"><code>veto oplock files = /*.exe/filename.ext/</code></em></td></tr></table></div></div><p><br class="example-break"> 484 484 </p><p> 485 485 <a class="link" href="smb.conf.5.html#OPLOCKBREAKWAITTIME" target="_top">oplock break wait time</a> is an <code class="filename">smb.conf</code> parameter … … 488 488 Oplock break wait time can only be configured globally in the <code class="filename">smb.conf</code> file as shown: 489 489 </p><p> 490 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2617 280"></a><em class="parameter"><code>oplock break wait time = 0 (default)</code></em></td></tr></table><p>490 </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2617333"></a><em class="parameter"><code>oplock break wait time = 0 (default)</code></em></td></tr></table><p> 491 491 </p><p> 492 492 <span class="emphasis"><em>Oplock break contention limit</em></span> is an <code class="filename">smb.conf</code> parameter that limits the … … 497 497 the entire server, in the <code class="filename">smb.conf</code> file as shown in <a class="link" href="locking.html#far3" title="Example 17.2. Configuration with Oplock Break Contention Limit">“Configuration with Oplock Break Contention Limit”</a>. 498 498 </p><p> 499 </p><div class="example"><a name="far3"></a><p class="title"><b>Example 17.2. Configuration with Oplock Break Contention Limit</b></p><div class="example-contents"><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id2617 354"></a><em class="parameter"><code>oplock break contention limit = 2 (default)</code></em></td></tr><tr><td> </td></tr><tr><td><em class="parameter"><code>[share_name]</code></em></td></tr><tr><td><a class="indexterm" name="id2617375"></a><em class="parameter"><code>oplock break contention limit = 2 (default)</code></em></td></tr></table></div></div><p><br class="example-break">500 </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617 393"></a>MS Windows Oplocks and Caching Controls</h2></div></div></div><p>499 </p><div class="example"><a name="far3"></a><p class="title"><b>Example 17.2. Configuration with Oplock Break Contention Limit</b></p><div class="example-contents"><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id2617407"></a><em class="parameter"><code>oplock break contention limit = 2 (default)</code></em></td></tr><tr><td> </td></tr><tr><td><em class="parameter"><code>[share_name]</code></em></td></tr><tr><td><a class="indexterm" name="id2617428"></a><em class="parameter"><code>oplock break contention limit = 2 (default)</code></em></td></tr></table></div></div><p><br class="example-break"> 500 </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617446"></a>MS Windows Oplocks and Caching Controls</h2></div></div></div><p> 501 501 There is a known issue when running applications (like Norton Antivirus) on a Windows 2000/ XP 502 502 workstation computer that can affect any application attempting to access shared database files … … 513 513 have oplocks disabled in order to minimize the risk of data file corruption. 514 514 This includes Windows 9x/Me, Windows NT, Windows 200x, and Windows XP. 515 <sup>[<a name="id26174 25" href="#ftn.id2617425" class="footnote">5</a>]</sup>515 <sup>[<a name="id2617478" href="#ftn.id2617478" class="footnote">5</a>]</sup> 516 516 </p><p> 517 517 If you are using a Windows NT family workstation in place of a server, you must also … … 591 591 writes or locks at this point, they need not respond to the break-to-none advisory; 592 592 all they need do is invalidate locally cashed read-ahead data. 593 </p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617 580"></a>Workstation Service Entries</h3></div></div></div><pre class="programlisting">593 </p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617633"></a>Workstation Service Entries</h3></div></div></div><pre class="programlisting"> 594 594 \HKEY_LOCAL_MACHINE\System\ 595 595 CurrentControlSet\Services\LanmanWorkstation\Parameters … … 600 600 This indicates whether the redirector should use oplocks performance 601 601 enhancement. This parameter should be disabled only to isolate problems. 602 </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id26176 02"></a>Server Service Entries</h3></div></div></div><pre class="programlisting">602 </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617655"></a>Server Service Entries</h3></div></div></div><pre class="programlisting"> 603 603 \HKEY_LOCAL_MACHINE\System\ 604 604 CurrentControlSet\Services\LanmanServer\Parameters … … 629 629 request. Smaller values can allow detection of crashed clients more quickly but can 630 630 potentially cause loss of cached data. 631 </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617 668"></a>Persistent Data Corruption</h2></div></div></div><p>631 </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617721"></a>Persistent Data Corruption</h2></div></div></div><p> 632 632 If you have applied all of the settings discussed in this chapter but data corruption problems 633 633 and other symptoms persist, here are some additional things to check out. … … 640 640 to the new one. There are several known methods for doing this that can be found in 641 641 our knowledge base. 642 </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617 693"></a>Common Errors</h2></div></div></div><p>642 </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617747"></a>Common Errors</h2></div></div></div><p> 643 643 In some sites locking problems surface as soon as a server is installed; in other sites 644 644 locking problems may not surface for a long time. Almost without exception, when a locking … … 670 670 Make sure that you give as much information as you possibly can to help isolate the 671 671 cause and to allow replication of the problem (an essential step in problem isolation and correction). 672 </p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617 761"></a>locking.tdb Error Messages</h3></div></div></div><p>672 </p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617814"></a>locking.tdb Error Messages</h3></div></div></div><p> 673 673 “<span class="quote"> 674 674 We are seeing lots of errors in the Samba logs, like: … … 684 684 </p><p> 685 685 This error indicates a corrupted tdb. Stop all instances of smbd, delete locking.tdb, and restart smbd. 686 </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617 791"></a>Problems Saving Files in MS Office on Windows XP</h3></div></div></div><a class="indexterm" name="id2617798"></a><p>This is a bug in Windows XP. More information can be686 </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617844"></a>Problems Saving Files in MS Office on Windows XP</h3></div></div></div><a class="indexterm" name="id2617851"></a><p>This is a bug in Windows XP. More information can be 687 687 found in <a class="ulink" href="http://support.microsoft.com/?id=812937" target="_top">Microsoft Knowledge Base article 812937</a></p>. 688 688 689 </div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id26178 16"></a>Long Delays Deleting Files over Network with XP SP1</h3></div></div></div><p>“<span class="quote">It sometimes takes approximately 35 seconds to delete files over the network after XP SP1 has been applied.</span>”</p><a class="indexterm" name="id2617828"></a><p>This is a bug in Windows XP. More information can be found in <a class="ulink" href="http://support.microsoft.com/?id=811492" target="_top">689 </div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2617869"></a>Long Delays Deleting Files over Network with XP SP1</h3></div></div></div><p>“<span class="quote">It sometimes takes approximately 35 seconds to delete files over the network after XP SP1 has been applied.</span>”</p><a class="indexterm" name="id2617881"></a><p>This is a bug in Windows XP. More information can be found in <a class="ulink" href="http://support.microsoft.com/?id=811492" target="_top"> 690 690 Microsoft Knowledge Base article 811492</a></p>. 691 </div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617 847"></a>Additional Reading</h2></div></div></div><p>691 </div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2617901"></a>Additional Reading</h2></div></div></div><p> 692 692 You may want to check for an updated documentation regarding file and record locking issues on the Microsoft 693 693 <a class="ulink" href="http://support.microsoft.com/" target="_top">Support</a> web site. Additionally, search for the word … … 696 696 Section of the Microsoft MSDN Library on opportunistic locking: 697 697 </p><p> 698 <a class="indexterm" name="id2617 884"></a>698 <a class="indexterm" name="id2617937"></a> 699 699 Microsoft Knowledge Base, “<span class="quote">Maintaining Transactional Integrity with OPLOCKS</span>”, 700 700 Microsoft Corporation, April 1999, <a class="ulink" href="http://support.microsoft.com/?id=224992" target="_top">Microsoft 701 701 KB Article 224992</a>. 702 702 </p><p> 703 <a class="indexterm" name="id26179 08"></a>703 <a class="indexterm" name="id2617961"></a> 704 704 Microsoft Knowledge Base, “<span class="quote">Configuring Opportunistic Locking in Windows 2000</span>”, 705 705 Microsoft Corporation, April 2001 <a class="ulink" href="http://support.microsoft.com/?id=296264" target="_top">Microsoft KB Article 296264</a>. 706 706 </p><p> 707 <a class="indexterm" name="id26179 32"></a>707 <a class="indexterm" name="id2617985"></a> 708 708 Microsoft Knowledge Base, “<span class="quote">PC Ext: Explanation of Opportunistic Locking on Windows NT</span>”, 709 709 Microsoft Corporation, April 1995 <a class="ulink" href="http://support.microsoft.com/?id=129202" target="_top">Microsoft 710 710 KB Article 129202</a>. 711 </p></div><div class="footnotes"><br><hr width="100" align="left"><div class="footnote"><p><sup>[<a name="ftn.id26174 25" href="#id2617425" class="para">5</a>] </sup>Microsoft has documented this in Knowledge Base article 300216.</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="AccessControls.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="optional.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="securing-samba.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 16. File, Directory, and Share Access Controls </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 18. Securing Samba</td></tr></table></div></body></html>711 </p></div><div class="footnotes"><br><hr width="100" align="left"><div class="footnote"><p><sup>[<a name="ftn.id2617478" href="#id2617478" class="para">5</a>] </sup>Microsoft has documented this in Knowledge Base article 300216.</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="AccessControls.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="optional.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="securing-samba.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 16. File, Directory, and Share Access Controls </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 18. Securing Samba</td></tr></table></div></body></html>
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