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diff --git a/docs/htmldocs/Samba3-HOWTO/speed.html b/docs/htmldocs/Samba3-HOWTO/speed.html new file mode 100644 index 0000000000..a848b34012 --- /dev/null +++ b/docs/htmldocs/Samba3-HOWTO/speed.html @@ -0,0 +1,174 @@ +<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 44. Samba Performance Tuning</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.71.0"><link rel="start" href="index.html" title="The Official Samba-3 HOWTO and Reference Guide"><link rel="up" href="Appendix.html" title="Part VI. Reference Section"><link rel="prev" href="Other-Clients.html" title="Chapter 43. Samba and Other CIFS Clients"><link rel="next" href="ch-ldap-tls.html" title="Chapter 45. LDAP and Transport Layer Security"></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 44. Samba Performance Tuning</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="Other-Clients.html">Prev</a> </td><th width="60%" align="center">Part VI. Reference Section</th><td width="20%" align="right"> <a accesskey="n" href="ch-ldap-tls.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="speed"></a>Chapter 44. Samba Performance Tuning</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Paul</span> <span class="surname">Cochrane</span></h3><div class="affiliation"><span class="orgname">Dundee Limb Fitting Centre<br></span><div class="address"><p><code class="email"><<a href="mailto:paulc@dth.scot.nhs.uk">paulc@dth.scot.nhs.uk</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="surname">Vernooij</span></h3><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><code class="email"><<a 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="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a href="mailto:jht@samba.org">jht@samba.org</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="speed.html#id445026">Comparisons</a></span></dt><dt><span class="sect1"><a href="speed.html#id445055">Socket Options</a></span></dt><dt><span class="sect1"><a href="speed.html#id445132">Read Size</a></span></dt><dt><span class="sect1"><a href="speed.html#id445163">Max Xmit</a></span></dt><dt><span class="sect1"><a href="speed.html#id445201">Log Level</a></span></dt><dt><span class="sect1"><a href="speed.html#id445220">Read Raw</a></span></dt><dt><span class="sect1"><a href="speed.html#id445265">Write Raw</a></span></dt><dt><span class="sect1"><a href="speed.html#id445302">Slow Logins</a></span></dt><dt><span class="sect1"><a href="speed.html#id445320">Client Tuning</a></span></dt><dt><span class="sect1"><a href="speed.html#id445339">Samba Performance Problem Due to Changing Linux Kernel</a></span></dt><dt><span class="sect1"><a href="speed.html#id445422">Corrupt tdb Files</a></span></dt><dt><span class="sect1"><a href="speed.html#id445511">Samba Performance is Very Slow</a></span></dt></dl></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445026"></a>Comparisons</h2></div></div></div><p> +The Samba server uses TCP to talk to the client, so if you are +trying to see if it performs well, you should really compare it to +programs that use the same protocol. The most readily available +programs for file transfer that use TCP are ftp or another TCP-based +SMB server. +</p><p> +If you want to test against something like an NT or Windows for Workgroups server, then +you will have to disable all but TCP on either the client or +server. Otherwise, you may well be using a totally different protocol +(such as NetBEUI) and comparisons may not be valid. +</p><p> +Generally, you should find that Samba performs similarly to ftp at raw +transfer speed. It should perform quite a bit faster than NFS, +although this depends on your system. +</p><p> +Several people have done comparisons between Samba and Novell, NFS, or +Windows NT. In some cases Samba performed the best, in others the worst. I +suspect the biggest factor is not Samba versus some other system, but the +hardware and drivers used on the various systems. Given similar +hardware, Samba should certainly be competitive in speed with other +systems. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445055"></a>Socket Options</h2></div></div></div><p> +There are a number of socket options that can greatly affect the +performance of a TCP-based server like Samba. +</p><p> +The socket options that Samba uses are settable both on the command +line with the <code class="option">-O</code> option and in the <code class="filename">smb.conf</code> file. +</p><p> +The <a class="indexterm" name="id445081"></a>socket options section of the <code class="filename">smb.conf</code> manual page describes how +to set these and gives recommendations. +</p><p> +Getting the socket options correct can make a big difference to your +performance, but getting them wrong can degrade it by just as +much. The correct settings are very dependent on your local network. +</p><p> +The socket option TCP_NODELAY is the one that seems to make the biggest single difference +for most networks. Many people report that adding +<a class="indexterm" name="id445104"></a>socket options = TCP_NODELAY +doubles the read performance of a Samba drive. The best explanation I have seen for +this is that the Microsoft TCP/IP stack is slow in sending TCP ACKs. +</p><p> +There have been reports that setting <em class="parameter"><code>socket options = SO_RCVBUF=8192</code></em> in smb.conf +can seriously degrade Samba performance on the loopback adaptor (IP Address 127.0.0.1). It is strongly +recommended that before specifying any settings for <em class="parameter"><code>socket options</code></em>, the effect +first be quantitatively measured on the server being configured. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445132"></a>Read Size</h2></div></div></div><p> +The option <a class="indexterm" name="id445140"></a>read size affects the overlap of disk +reads/writes with network reads/writes. If the amount of data being +transferred in several of the SMB commands (currently SMBwrite, SMBwriteX, and +SMBreadbraw) is larger than this value, then the server begins writing +the data before it has received the whole packet from the network, or +in the case of SMBreadbraw, it begins writing to the network before +all the data has been read from disk. +</p><p> +This overlapping works best when the speeds of disk and network access +are similar, having little effect when the speed of one is much +greater than the other. +</p><p> +The default value is 16384, but little experimentation has been +done as yet to determine the optimal value, and it is likely that the best +value will vary greatly between systems anyway. A value over 65536 is +pointless and will cause you to allocate memory unnecessarily. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445163"></a>Max Xmit</h2></div></div></div><p> + At startup the client and server negotiate a <em class="parameter"><code>maximum transmit</code></em> size, +which limits the size of nearly all SMB commands. You can set the +maximum size that Samba will negotiate using the <a class="indexterm" name="id445179"></a>max xmit option +in <code class="filename">smb.conf</code>. Note that this is the maximum size of SMB requests that +Samba will accept, but not the maximum size that the client will accept. +The client maximum receive size is sent to Samba by the client, and Samba +honors this limit. +</p><p> +It defaults to 65536 bytes (the maximum), but it is possible that some +clients may perform better with a smaller transmit unit. Trying values +of less than 2048 is likely to cause severe problems. +In most cases the default is the best option. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445201"></a>Log Level</h2></div></div></div><p> +If you set the log level (also known as <a class="indexterm" name="id445209"></a>debug level) higher than 2, +then you may suffer a large drop in performance. This is because the +server flushes the log file after each operation, which can be quite +expensive. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445220"></a>Read Raw</h2></div></div></div><p> +The <a class="indexterm" name="id445228"></a>read raw operation is designed to be an optimized, low-latency +file read operation. A server may choose to not support it, +however, and Samba makes support for <a class="indexterm" name="id445236"></a>read raw optional, with it +being enabled by default. +</p><p> +In some cases clients do not handle <a class="indexterm" name="id445247"></a>read raw very well and actually +get lower performance using it than they get using the conventional +read operations, so you might like to try <a class="indexterm" name="id445255"></a>read raw = no and see what happens on your +network. It might lower, raise, or not affect your performance. Only +testing can really tell. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445265"></a>Write Raw</h2></div></div></div><p> +The <a class="indexterm" name="id445273"></a>write raw operation is designed to be an optimized, low-latency +file write operation. A server may choose to not support it, however, and Samba makes support for +<a class="indexterm" name="id445282"></a>write raw optional, with it being enabled by default. +</p><p> +Some machines may find <a class="indexterm" name="id445292"></a>write raw slower than normal write, in which +case you may wish to change this option. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445302"></a>Slow Logins</h2></div></div></div><p> +Slow logins are almost always due to the password checking time. Using +the lowest practical <a class="indexterm" name="id445311"></a>password level will improve things. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445320"></a>Client Tuning</h2></div></div></div><p> +Often a speed problem can be traced to the client. The client (for +example Windows for Workgroups) can often be tuned for better TCP +performance. Check the sections on the various clients in +<a href="Other-Clients.html" title="Chapter 43. Samba and Other CIFS Clients">Samba and Other CIFS Clients</a>. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445339"></a>Samba Performance Problem Due to Changing Linux Kernel</h2></div></div></div><p> +A user wrote the following to the mailing list: +</p><div class="blockquote"><blockquote class="blockquote"><p> +<a class="indexterm" name="id445353"></a> +<a class="indexterm" name="id445359"></a> +I am running Gentoo on my server and Samba 2.2.8a. Recently I changed kernel versions from +<code class="filename">linux-2.4.19-gentoo-r10</code> to <code class="filename">linux-2.4.20-wolk4.0s</code>. Now I have a +performance issue with Samba. Many of you will probably say, “<span class="quote">Move to vanilla sources!</span>” Well, I +tried that and it didn't work. I have a 100MB LAN and two computers (Linux and Windows 2000). The Linux server +shares directories with DivX files, the client (Windows 2000) plays them via LAN. Before, when I was running +the 2.4.19 kernel, everything was fine, but now movies freeze and stop. I tried moving files between the +server and Windows, and it is terribly slow. +</p></blockquote></div><p> +The answer he was given is: +</p><div class="blockquote"><blockquote class="blockquote"><p> +<a class="indexterm" name="id445396"></a> +<a class="indexterm" name="id445403"></a> +<a class="indexterm" name="id445410"></a> +Grab the mii-tool and check the duplex settings on the NIC. My guess is that it is a link layer issue, not an +application layer problem. Also run ifconfig and verify that the framing error, collisions, and so on, look +normal for ethernet. +</p></blockquote></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445422"></a>Corrupt tdb Files</h2></div></div></div><p> +<a class="indexterm" name="id445430"></a> +<a class="indexterm" name="id445436"></a> +<a class="indexterm" name="id445443"></a> +Our Samba PDC server has been hosting three TB of data to our 500+ users [Windows NT/XP] for the last three +years using Samba without a problem. Today all shares went very slow. Also, the main smbd kept spawning new +processes, so we had 1600+ running SMDB's (normally we average 250). It crashed the SUN E3500 cluster twice. +After a lot of searching, I decided to <code class="literal">rm /var/locks/*.tdb</code>. Happy again. +</p><p> +<span class="emphasis"><em>Question:</em></span> Is there any method of keeping the *.tdb files in top condition, or +how can I detect early corruption? +</p><p> +<a class="indexterm" name="id445470"></a> +<a class="indexterm" name="id445477"></a> +<span class="emphasis"><em>Answer:</em></span> Yes, run <code class="literal">tdbbackup</code> each time after stopping nmbd and before starting nmbd. +</p><p> +<span class="emphasis"><em>Question:</em></span> What I also would like to mention is that the service latency seems +a lot lower than before the locks cleanup. Any ideas on keeping it top notch? +</p><p> +<span class="emphasis"><em>Answer:</em></span> Yes. Same answer as for previous question! +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id445511"></a>Samba Performance is Very Slow</h2></div></div></div><p> +<a class="indexterm" name="id445519"></a> +A site reported experiencing very baffling symptoms with MYOB Premier opening and +accessing its data files. Some operations on the file would take between 40 and +45 seconds. +</p><p> +<a class="indexterm" name="id445531"></a> +<a class="indexterm" name="id445538"></a> +It turned out that the printer monitor program running on the Windows +clients was causing the problems. From the logs, we saw activity coming +through with pauses of about 1 second. +</p><p> +<a class="indexterm" name="id445549"></a> +<a class="indexterm" name="id445556"></a> +Stopping the monitor software resulted in the networks access at normal +(quick) speed. Restarting the program caused the speed to slow down +again. The printer was a Canon LBP-810 and the relevant task was +something like CAPON (not sure on spelling). The monitor software +displayed a "printing now" dialog on the client during printing. +</p><p> +We discovered this by starting with a clean install of Windows and +trying the application at every step of the installation of other software +process (we had to do this many times). +</p><p> +Moral of the story: Check everything (other software included)! +</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="Other-Clients.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="Appendix.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch-ldap-tls.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 43. 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