| [218] | 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 3. Samba Architecture</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="SAMBA Developers Guide"><link rel="up" href="pt02.html" title="Part II. Samba Basics"><link rel="prev" href="pt02.html" title="Part II. Samba Basics"><link rel="next" href="debug.html" title="Chapter 4. The samba DEBUG system"></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 3. Samba Architecture</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pt02.html">Prev</a> </td><th width="60%" align="center">Part II. Samba Basics</th><td width="20%" align="right"> <a accesskey="n" href="debug.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="architecture"></a>Chapter 3. Samba Architecture</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Dan</span> <span class="surname">Shearer</span></h3></div></div><div><p class="pubdate"> November 1997</p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="architecture.html#id2556708">Introduction</a></span></dt><dt><span class="sect1"><a href="architecture.html#id2556751">Multithreading and Samba</a></span></dt><dt><span class="sect1"><a href="architecture.html#id2556783">Threading smbd</a></span></dt><dt><span class="sect1"><a href="architecture.html#id2556844">Threading nmbd</a></span></dt><dt><span class="sect1"><a href="architecture.html#id2556889">nbmd Design</a></span></dt></dl></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2556708"></a>Introduction</h2></div></div></div><p>
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| 2 | This document gives a general overview of how Samba works
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| 3 | internally. The Samba Team has tried to come up with a model which is
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| 4 | the best possible compromise between elegance, portability, security
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| 5 | and the constraints imposed by the very messy SMB and CIFS
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| 6 | protocol.
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| 7 | </p><p>
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| 8 | It also tries to answer some of the frequently asked questions such as:
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| 9 | </p><div class="orderedlist"><ol type="1"><li><p>
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| 10 | Is Samba secure when running on Unix? The xyz platform?
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| 11 | What about the root priveliges issue?
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| 12 | </p></li><li><p>Pros and cons of multithreading in various parts of Samba</p></li><li><p>Why not have a separate process for name resolution, WINS, and browsing?</p></li></ol></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2556751"></a>Multithreading and Samba</h2></div></div></div><p>
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| 13 | People sometimes tout threads as a uniformly good thing. They are very
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| 14 | nice in their place but are quite inappropriate for smbd. nmbd is
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| 15 | another matter, and multi-threading it would be very nice.
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| 16 | </p><p>
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| 17 | The short version is that smbd is not multithreaded, and alternative
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| 18 | servers that take this approach under Unix (such as Syntax, at the
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| 19 | time of writing) suffer tremendous performance penalties and are less
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| 20 | robust. nmbd is not threaded either, but this is because it is not
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| 21 | possible to do it while keeping code consistent and portable across 35
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| 22 | or more platforms. (This drawback also applies to threading smbd.)
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| 23 | </p><p>
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| 24 | The longer versions is that there are very good reasons for not making
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| 25 | smbd multi-threaded. Multi-threading would actually make Samba much
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| 26 | slower, less scalable, less portable and much less robust. The fact
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| 27 | that we use a separate process for each connection is one of Samba's
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| 28 | biggest advantages.
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| 29 | </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2556783"></a>Threading smbd</h2></div></div></div><p>
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| 30 | A few problems that would arise from a threaded smbd are:
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| 31 | </p><div class="orderedlist"><ol type="1"><li><p>
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| 32 | It's not only to create threads instead of processes, but you
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| 33 | must care about all variables if they have to be thread specific
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| 34 | (currently they would be global).
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| 35 | </p></li><li><p>
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