mirror of
https://github.com/nextcloud/desktop.git
synced 2024-12-18 20:02:17 +03:00
69bb51d7af
Thanks to Joe Brockmeier <zonker@opensuse.org> for proofreading.
732 lines
23 KiB
HTML
732 lines
23 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
|
|
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
|
<meta name="generator" content="AsciiDoc 8.2.7" />
|
|
<style type="text/css">
|
|
/* Debug borders */
|
|
p, li, dt, dd, div, pre, h1, h2, h3, h4, h5, h6 {
|
|
/*
|
|
border: 1px solid red;
|
|
*/
|
|
}
|
|
|
|
body {
|
|
margin: 1em 5% 1em 5%;
|
|
}
|
|
|
|
a {
|
|
color: blue;
|
|
text-decoration: underline;
|
|
}
|
|
a:visited {
|
|
color: fuchsia;
|
|
}
|
|
|
|
em {
|
|
font-style: italic;
|
|
color: navy;
|
|
}
|
|
|
|
strong {
|
|
font-weight: bold;
|
|
color: #083194;
|
|
}
|
|
|
|
tt {
|
|
color: navy;
|
|
}
|
|
|
|
h1, h2, h3, h4, h5, h6 {
|
|
color: #527bbd;
|
|
font-family: sans-serif;
|
|
margin-top: 1.2em;
|
|
margin-bottom: 0.5em;
|
|
line-height: 1.3;
|
|
}
|
|
|
|
h1, h2, h3 {
|
|
border-bottom: 2px solid silver;
|
|
}
|
|
h2 {
|
|
padding-top: 0.5em;
|
|
}
|
|
h3 {
|
|
float: left;
|
|
}
|
|
h3 + * {
|
|
clear: left;
|
|
}
|
|
|
|
div.sectionbody {
|
|
font-family: serif;
|
|
margin-left: 0;
|
|
}
|
|
|
|
hr {
|
|
border: 1px solid silver;
|
|
}
|
|
|
|
p {
|
|
margin-top: 0.5em;
|
|
margin-bottom: 0.5em;
|
|
}
|
|
|
|
ul, ol, li > p {
|
|
margin-top: 0;
|
|
}
|
|
|
|
pre {
|
|
padding: 0;
|
|
margin: 0;
|
|
}
|
|
|
|
span#author {
|
|
color: #527bbd;
|
|
font-family: sans-serif;
|
|
font-weight: bold;
|
|
font-size: 1.1em;
|
|
}
|
|
span#email {
|
|
}
|
|
span#revision {
|
|
font-family: sans-serif;
|
|
}
|
|
|
|
div#footer {
|
|
font-family: sans-serif;
|
|
font-size: small;
|
|
border-top: 2px solid silver;
|
|
padding-top: 0.5em;
|
|
margin-top: 4.0em;
|
|
}
|
|
div#footer-text {
|
|
float: left;
|
|
padding-bottom: 0.5em;
|
|
}
|
|
div#footer-badges {
|
|
float: right;
|
|
padding-bottom: 0.5em;
|
|
}
|
|
|
|
div#preamble,
|
|
div.tableblock, div.imageblock, div.exampleblock, div.verseblock,
|
|
div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
|
|
div.admonitionblock {
|
|
margin-right: 10%;
|
|
margin-top: 1.5em;
|
|
margin-bottom: 1.5em;
|
|
}
|
|
div.admonitionblock {
|
|
margin-top: 2.5em;
|
|
margin-bottom: 2.5em;
|
|
}
|
|
|
|
div.content { /* Block element content. */
|
|
padding: 0;
|
|
}
|
|
|
|
/* Block element titles. */
|
|
div.title, caption.title {
|
|
color: #527bbd;
|
|
font-family: sans-serif;
|
|
font-weight: bold;
|
|
text-align: left;
|
|
margin-top: 1.0em;
|
|
margin-bottom: 0.5em;
|
|
}
|
|
div.title + * {
|
|
margin-top: 0;
|
|
}
|
|
|
|
td div.title:first-child {
|
|
margin-top: 0.0em;
|
|
}
|
|
div.content div.title:first-child {
|
|
margin-top: 0.0em;
|
|
}
|
|
div.content + div.title {
|
|
margin-top: 0.0em;
|
|
}
|
|
|
|
div.sidebarblock > div.content {
|
|
background: #ffffee;
|
|
border: 1px solid silver;
|
|
padding: 0.5em;
|
|
}
|
|
|
|
div.listingblock {
|
|
margin-right: 0%;
|
|
}
|
|
div.listingblock > div.content {
|
|
border: 1px solid silver;
|
|
background: #f4f4f4;
|
|
padding: 0.5em;
|
|
}
|
|
|
|
div.quoteblock {
|
|
padding-left: 2.0em;
|
|
}
|
|
div.quoteblock > div.attribution {
|
|
padding-top: 0.5em;
|
|
text-align: right;
|
|
}
|
|
|
|
div.verseblock {
|
|
padding-left: 2.0em;
|
|
}
|
|
div.verseblock > div.content {
|
|
white-space: pre;
|
|
}
|
|
div.verseblock > div.attribution {
|
|
padding-top: 0.75em;
|
|
text-align: left;
|
|
}
|
|
/* DEPRECATED: Pre version 8.2.7 verse style literal block. */
|
|
div.verseblock + div.attribution {
|
|
text-align: left;
|
|
}
|
|
|
|
div.admonitionblock .icon {
|
|
vertical-align: top;
|
|
font-size: 1.1em;
|
|
font-weight: bold;
|
|
text-decoration: underline;
|
|
color: #527bbd;
|
|
padding-right: 0.5em;
|
|
}
|
|
div.admonitionblock td.content {
|
|
padding-left: 0.5em;
|
|
border-left: 2px solid silver;
|
|
}
|
|
|
|
div.exampleblock > div.content {
|
|
border-left: 2px solid silver;
|
|
padding: 0.5em;
|
|
}
|
|
|
|
div.imageblock div.content { padding-left: 0; }
|
|
div.imageblock img { border: 1px solid silver; }
|
|
span.image img { border-style: none; }
|
|
|
|
dl {
|
|
margin-top: 0.8em;
|
|
margin-bottom: 0.8em;
|
|
}
|
|
dt {
|
|
margin-top: 0.5em;
|
|
margin-bottom: 0;
|
|
font-style: normal;
|
|
}
|
|
dd > *:first-child {
|
|
margin-top: 0.1em;
|
|
}
|
|
|
|
ul, ol {
|
|
list-style-position: outside;
|
|
}
|
|
div.olist > ol {
|
|
list-style-type: decimal;
|
|
}
|
|
div.olist2 > ol {
|
|
list-style-type: lower-alpha;
|
|
}
|
|
|
|
div.tableblock > table {
|
|
border: 3px solid #527bbd;
|
|
}
|
|
thead {
|
|
font-family: sans-serif;
|
|
font-weight: bold;
|
|
}
|
|
tfoot {
|
|
font-weight: bold;
|
|
}
|
|
|
|
div.hlist {
|
|
margin-top: 0.8em;
|
|
margin-bottom: 0.8em;
|
|
}
|
|
div.hlist td {
|
|
padding-bottom: 15px;
|
|
}
|
|
td.hlist1 {
|
|
vertical-align: top;
|
|
font-style: normal;
|
|
padding-right: 0.8em;
|
|
}
|
|
td.hlist2 {
|
|
vertical-align: top;
|
|
}
|
|
|
|
@media print {
|
|
div#footer-badges { display: none; }
|
|
}
|
|
|
|
div#toctitle {
|
|
color: #527bbd;
|
|
font-family: sans-serif;
|
|
font-size: 1.1em;
|
|
font-weight: bold;
|
|
margin-top: 1.0em;
|
|
margin-bottom: 0.1em;
|
|
}
|
|
|
|
div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
|
|
margin-top: 0;
|
|
margin-bottom: 0;
|
|
}
|
|
div.toclevel2 {
|
|
margin-left: 2em;
|
|
font-size: 0.9em;
|
|
}
|
|
div.toclevel3 {
|
|
margin-left: 4em;
|
|
font-size: 0.9em;
|
|
}
|
|
div.toclevel4 {
|
|
margin-left: 6em;
|
|
font-size: 0.9em;
|
|
}
|
|
/* Workarounds for IE6's broken and incomplete CSS2. */
|
|
|
|
div.sidebar-content {
|
|
background: #ffffee;
|
|
border: 1px solid silver;
|
|
padding: 0.5em;
|
|
}
|
|
div.sidebar-title, div.image-title {
|
|
color: #527bbd;
|
|
font-family: sans-serif;
|
|
font-weight: bold;
|
|
margin-top: 0.0em;
|
|
margin-bottom: 0.5em;
|
|
}
|
|
|
|
div.listingblock div.content {
|
|
border: 1px solid silver;
|
|
background: #f4f4f4;
|
|
padding: 0.5em;
|
|
}
|
|
|
|
div.quoteblock-attribution {
|
|
padding-top: 0.5em;
|
|
text-align: right;
|
|
}
|
|
|
|
div.verseblock-content {
|
|
white-space: pre;
|
|
}
|
|
div.verseblock-attribution {
|
|
padding-top: 0.75em;
|
|
text-align: left;
|
|
}
|
|
|
|
div.exampleblock-content {
|
|
border-left: 2px solid silver;
|
|
padding-left: 0.5em;
|
|
}
|
|
|
|
/* IE6 sets dynamically generated links as visited. */
|
|
div#toc a:visited { color: blue; }
|
|
|
|
/* Because IE6 child selector is broken. */
|
|
div.olist2 ol {
|
|
list-style-type: lower-alpha;
|
|
}
|
|
div.olist2 div.olist ol {
|
|
list-style-type: decimal;
|
|
}
|
|
</style>
|
|
<script type="text/javascript">
|
|
/*<![CDATA[*/
|
|
window.onload = function(){generateToc(2)}
|
|
/* Author: Mihai Bazon, September 2002
|
|
* http://students.infoiasi.ro/~mishoo
|
|
*
|
|
* Table Of Content generator
|
|
* Version: 0.4
|
|
*
|
|
* Feel free to use this script under the terms of the GNU General Public
|
|
* License, as long as you do not remove or alter this notice.
|
|
*/
|
|
|
|
/* modified by Troy D. Hanson, September 2006. License: GPL */
|
|
/* modified by Stuart Rackham, October 2006. License: GPL */
|
|
|
|
function getText(el) {
|
|
var text = "";
|
|
for (var i = el.firstChild; i != null; i = i.nextSibling) {
|
|
if (i.nodeType == 3 /* Node.TEXT_NODE */) // IE doesn't speak constants.
|
|
text += i.data;
|
|
else if (i.firstChild != null)
|
|
text += getText(i);
|
|
}
|
|
return text;
|
|
}
|
|
|
|
function TocEntry(el, text, toclevel) {
|
|
this.element = el;
|
|
this.text = text;
|
|
this.toclevel = toclevel;
|
|
}
|
|
|
|
function tocEntries(el, toclevels) {
|
|
var result = new Array;
|
|
var re = new RegExp('[hH]([2-'+(toclevels+1)+'])');
|
|
// Function that scans the DOM tree for header elements (the DOM2
|
|
// nodeIterator API would be a better technique but not supported by all
|
|
// browsers).
|
|
var iterate = function (el) {
|
|
for (var i = el.firstChild; i != null; i = i.nextSibling) {
|
|
if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
|
|
var mo = re.exec(i.tagName)
|
|
if (mo)
|
|
result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
|
|
iterate(i);
|
|
}
|
|
}
|
|
}
|
|
iterate(el);
|
|
return result;
|
|
}
|
|
|
|
// This function does the work. toclevels = 1..4.
|
|
function generateToc(toclevels) {
|
|
var toc = document.getElementById("toc");
|
|
var entries = tocEntries(document.getElementsByTagName("body")[0], toclevels);
|
|
for (var i = 0; i < entries.length; ++i) {
|
|
var entry = entries[i];
|
|
if (entry.element.id == "")
|
|
entry.element.id = "toc" + i;
|
|
var a = document.createElement("a");
|
|
a.href = "#" + entry.element.id;
|
|
a.appendChild(document.createTextNode(entry.text));
|
|
var div = document.createElement("div");
|
|
div.appendChild(a);
|
|
div.className = "toclevel" + entry.toclevel;
|
|
toc.appendChild(div);
|
|
}
|
|
if (entries.length == 0)
|
|
document.getElementById("header").removeChild(toc);
|
|
}
|
|
/*]]>*/
|
|
</script>
|
|
<title>CSYNC User Guide</title>
|
|
</head>
|
|
<body>
|
|
<div id="header">
|
|
<h1>CSYNC User Guide</h1>
|
|
<span id="author">Andreas Schneider</span><br />
|
|
<span id="email"><tt><<a href="mailto:mail@cynapses.org">mail@cynapses.org</a>></tt></span><br />
|
|
<div id="toc">
|
|
<div id="toctitle">Table of Contents</div>
|
|
<noscript><p><b>JavaScript must be enabled in your browser to display the table of contents.</b></p></noscript>
|
|
</div>
|
|
</div>
|
|
<div id="preamble">
|
|
<div class="sectionbody">
|
|
<div class="para"><p>csync is a lightweight utility to synchronize files between two directories
|
|
on a system, or between multiple systems.</p></div>
|
|
<div class="para"><p>It synchronizes bidirectional and allows to keep two copies of files and
|
|
directories in sync. It uses uses widly adopted protocols, like smb or sftp so
|
|
that there is no need for a server component of csync. It is a user-level
|
|
program which means you don't need to be a superuser.</p></div>
|
|
<div class="para"><p>Together with a PAM modules the intention is to provide Roaming Home
|
|
Directories for Linux.</p></div>
|
|
</div>
|
|
</div>
|
|
<h2 id="_introduction">1. Introduction</h2>
|
|
<div class="sectionbody">
|
|
<div class="para"><p>It is often the case that we have multiple copies (called replicas) of a
|
|
filesystem or part of a filesystem (for example on a notebook and on a desktop
|
|
computer). Changes to each replica are often made independently and as a
|
|
result they do not contain the same information. In that case a file
|
|
synchronizer is used to make them consistent again, without losing any
|
|
information.</p></div>
|
|
<div class="para"><p>The goal is to detect conflicting updates (files which has been
|
|
modified) and propagate non-conflicting updates to each replica. If there
|
|
are no conflicts left we are done and the replicas are identical.</p></div>
|
|
</div>
|
|
<h2 id="_basics">2. Basics</h2>
|
|
<div class="sectionbody">
|
|
<div class="para"><p>This section describes some basics you might need to understand how file
|
|
synchronization works.</p></div>
|
|
<h3 id="_paths">2.1. Paths</h3><div style="clear:left"></div>
|
|
<div class="para"><p>A path normally refers to a point with a set of files which should be
|
|
synchronized. It is specified relative to the root of the replica. The path is
|
|
just a sequence of names separated by <em>/</em>.</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<img src="./images/icons/note.png" alt="Note" />
|
|
</td>
|
|
<td class="content">The path separator is always a forward slash <em>/</em>, even for Windows.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="para"><p>csync always uses the absolute path. This could be <em>/home/gladiac</em> or
|
|
for sftp <em>sftp://gladiac:secret@myserver/home/gladiac</em>.</p></div>
|
|
<h3 id="_what_is_an_update">2.2. What is an update?</h3><div style="clear:left"></div>
|
|
<div class="para"><p>The contents of a path could be a file, a directory or a symbolic link
|
|
(symbolic links are not supported yet). To be more precise, if the path refers
|
|
to:</p></div>
|
|
<div class="ilist"><ul>
|
|
<li>
|
|
<p>
|
|
a regular file, the the contents of the file are the byte stream and the
|
|
metatdata of the file.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
a directory, then the content is the metadata of the directory.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
a symbolic link, then the content is the named file the link points to.
|
|
</p>
|
|
</li>
|
|
</ul></div>
|
|
<div class="para"><p>csync keeps a record of each path which has been successfully synchronized. The
|
|
path gets compared with the record and if it has changed since the last
|
|
synchronization, we have an update. This is done by comparing the modification
|
|
or change (modification time of the metadata) time.</p></div>
|
|
<h3 id="_what_is_a_conflict">2.3. What is a conflict?</h3><div style="clear:left"></div>
|
|
<div class="para"><p>A path is conflicting if it fulfills the following conditions:</p></div>
|
|
<div class="olist"><ol>
|
|
<li>
|
|
<p>
|
|
it has been updated in one replica,
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
it or any of its descendants has been updated on the other replica too, and
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
its contents in are not identical.
|
|
</p>
|
|
</li>
|
|
</ol></div>
|
|
</div>
|
|
<h2 id="_file_synchronization">3. File Synchronization</h2>
|
|
<div class="sectionbody">
|
|
<div class="para"><p>The main goal of a file synchronizer is correctness. It changes whole or
|
|
separated pieces of a users file system. So a user is not able to monitor the
|
|
complete file synchronization process, and the synchronizer is in a position
|
|
where it can damage the file system. It is important that the implementation
|
|
behaves correctly under all conditions, even if there is an unexpected error
|
|
(for example, disk full).</p></div>
|
|
<div class="para"><p>On problem concerning correctness is the handling of conflicts. Each file
|
|
synchronizer tries to propagate conflicting changes to the other replica. At
|
|
the end both replicas should be identical. There are different strategies to
|
|
fulfill these goals.</p></div>
|
|
<div class="para"><p>csync is a 3-phase file synchronizer. The desicion for this design was that
|
|
user interaction should be possible and it should be easy to understand the
|
|
process. The 3 phases are update detection, reconciliation and propagation.
|
|
These will be described in the following sections.</p></div>
|
|
<h3 id="_update_detection">3.1. Update detection</h3><div style="clear:left"></div>
|
|
<div class="para"><p>There are differnt strategies to do update detection. csync uses a state-based
|
|
modtime-inode update detector. This means it uses a the modification time to
|
|
detect updates. It doesn't require much resources. A record of each file is
|
|
stored in a database (called statedb) and compared with the current
|
|
modification time during update detection. If the file has changed since the
|
|
last synchronization a instruction is set to evaluate it during the
|
|
reconcilation phase. If we don't have a record for a file we invastigate, it is
|
|
marked as new.</p></div>
|
|
<div class="para"><p>There is a problem to detect renaming of files. This is sovled by the record we
|
|
store in the statedb too. If we don't find the file by the name in the database
|
|
we search for the inode number. If the inode number is found then the file has
|
|
been renamed.</p></div>
|
|
<h3 id="_reconciliation">3.2. Reconciliation</h3><div style="clear:left"></div>
|
|
<div class="para"><p>The most improtant component is the update detector, because the reconciler depends
|
|
on it. The correctness of reconciler is mandatory because it can damage a
|
|
filesystem. It decides which file:</p></div>
|
|
<div class="ilist"><ul>
|
|
<li>
|
|
<p>
|
|
Stays untouched
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
Has a conflict
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
Gets synchronized
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
or is <strong>deleted</strong>
|
|
</p>
|
|
</li>
|
|
</ul></div>
|
|
<div class="para"><p>A wrong decision of the reconciler leads in most cases to a loss of data. So there
|
|
are several conditions a the file synchronizer has to follow.</p></div>
|
|
<h4 id="_algorithms">3.2.1. Algorithms</h4>
|
|
<div class="para"><p>For conflict resolution several different algorithms could be implemented. The
|
|
most common algorithm are the merge and and the conflict algorithm. The first
|
|
is a batch algortihm and the second is one which needs user interaction.</p></div>
|
|
<h5 id="_merge_algorithm">Merge algorithm</h5>
|
|
<div class="para"><p>The merge algorithm is an algorithm which doesn't need any user interaction. It
|
|
is simple and used for example by Microsoft for Roaming Proflies. If it detects
|
|
a conflict (the same file changed on both replicas) then it will use the most
|
|
recent file and overwrite the other. This means you can loose some data, but
|
|
normally you want the latest file.</p></div>
|
|
<h5 id="_conflict_algorithm">Conflict algorithm</h5>
|
|
<div class="para"><p>This is not implemented yet.</p></div>
|
|
<div class="para"><p>If a file has a conflict the user has to decicde which file should be used.</p></div>
|
|
<h3 id="_propagation">3.3. Propagation</h3><div style="clear:left"></div>
|
|
<div class="para"><p>The next instance of the file synchronizer the propagator. It uses the
|
|
calculated records to apply them on the current replica.</p></div>
|
|
<div class="para"><p>The propagator uses a 2-phase-commit mechanism to simulate an atomic filesystem
|
|
operation.</p></div>
|
|
<div class="para"><p>In the first phase we copy the file to a temporary file on the opposite
|
|
replica. This has the advantage that we can check if file which has been copied
|
|
to the opposite replica has been transfered successfully. If the connection
|
|
gets interruppted during the transfer we still have the orignal states of the
|
|
file. This means no data will be lost.</p></div>
|
|
<div class="para"><p>In the second phase the the file on the opposite replica will be overwritten by
|
|
the temporary file.</p></div>
|
|
<div class="para"><p>After a successfull propagation we have to merge the trees to reflect the
|
|
current state of the filesystem tree. This updated tree will be written as a
|
|
journal into a database. The database is called the state database. It will be
|
|
used during the update detection of the next synchronization. See above.</p></div>
|
|
<h3 id="_robustness">3.4. Robustness</h3><div style="clear:left"></div>
|
|
<div class="para"><p>This is a really important topic. The file synchronizer should not crash and if
|
|
it has crashed, there should be no loss of data. To achieve this goal there are
|
|
several mechanisms to prevent this. These mechnanisms will be discussed in the
|
|
following sections.</p></div>
|
|
<h4 id="_crash_resistance">3.4.1. Crash resistance</h4>
|
|
<div class="para"><p>The synchronization process can be interrupted by different events, this can
|
|
be:</p></div>
|
|
<div class="ilist"><ul>
|
|
<li>
|
|
<p>
|
|
the system could be halted due to errors.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
the disk could be full or the quota exceeded.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
the network or power cable could be pulled out.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
the user could force a stop of the synchronization process.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
different communication errors could occur.
|
|
</p>
|
|
</li>
|
|
</ul></div>
|
|
<div class="para"><p>That no data will be lost due to the occurance we enforce the following
|
|
invariant:</p></div>
|
|
<div class="admonitionblock">
|
|
<table><tr>
|
|
<td class="icon">
|
|
<img src="./images/icons/important.png" alt="Important" />
|
|
</td>
|
|
<td class="content">At every moment of the synchronization each file has either its
|
|
original content or its correct final content.</td>
|
|
</tr></table>
|
|
</div>
|
|
<div class="para"><p>This means, that the original content can not be incorrect, no data can't be
|
|
lost until we overwrite it after a successful synchronization.
|
|
So each interupted synchronization process is a partial sync and can be
|
|
continued and completed by simply running csync again. The only problem could
|
|
be an error of the filesystem. So we reach this invariant only approximatly.</p></div>
|
|
<h4 id="_transfer_errors">3.4.2. Transfer errors</h4>
|
|
<div class="para"><p>With the Two-Phase-Commit we check the file size after the file has
|
|
transferred. So we can detect transfer errors. Better would be a transfer
|
|
protocol with checksums. We may do this in the future.</p></div>
|
|
<div class="para"><p>Future filesystems, like btrfs, will help to compare checksums instead of the
|
|
filesize. This will make the synchronization safer. This doen't mean that it is
|
|
unsafe now, but checkums are better then just filesize checks.</p></div>
|
|
<h4 id="_database_loss">3.4.3. Database loss</h4>
|
|
<div class="para"><p>It could be possible, that the state database get corrupted. If this happens
|
|
all files get evaluated. In this case the file synchronizer wont delete any
|
|
file, but it could occur that deleted files will be restored from the other
|
|
replica.</p></div>
|
|
<div class="para"><p>To prevent a corruption or loss of the database if an error occurs or the user
|
|
forces an abort, the synchronizer is working on a copy of the database and will
|
|
use a Two-Phase-Commit to save it at the end.</p></div>
|
|
</div>
|
|
<h2 id="_getting_started">4. Getting started</h2>
|
|
<div class="sectionbody">
|
|
<h3 id="_installing_csync">4.1. Installing csync</h3><div style="clear:left"></div>
|
|
<div class="para"><p>See the <tt>README</tt> and <tt>INSTALL</tt> files for install prerequisites and
|
|
procedures. Packagers take a look at <a href="#X90">Appendix B: Packager Notes</a>.</p></div>
|
|
<h3 id="_using_the_commandline_client">4.2. Using the commandline client</h3><div style="clear:left"></div>
|
|
<div class="para"><p>The synopsis of the commandline client is</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync [OPTION...] SOURCE DESTINATION</tt></pre>
|
|
</div></div>
|
|
<div class="para"><p>It synchronizes the content of SOURCE with DESTINATION and vice versa. The
|
|
DESTINATION can be a local directory or a remote file server.</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync /home/csync scheme://user:password@server:port/full/path</tt></pre>
|
|
</div></div>
|
|
<h4 id="_examples">4.2.1. Examples</h4>
|
|
<div class="para"><p>To synchronize two local directories:</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync /home/csync/replica1 /home/csync/relplica2</tt></pre>
|
|
</div></div>
|
|
<div class="para"><p>Two synchronizer a local directory with an smb server, use</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync /home/csync smb://rupert.galaxy.site/Users/csync</tt></pre>
|
|
</div></div>
|
|
<div class="para"><p>If you use kerberos you don't have to specify a username or a password. If you
|
|
don't use kerberos, the commandline client will ask about the user and the
|
|
password.
|
|
If you don't want to be ask, you can specify it on the commandline:</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync /home/csync smb://csync:secret@rupert.galaxy.site/Users/csync</tt></pre>
|
|
</div></div>
|
|
<div class="para"><p>If you use the sftp protocol and want to specify a port, you do it the
|
|
following way:</p></div>
|
|
<div class="literalblock">
|
|
<div class="content">
|
|
<pre><tt>csync /home/csync sftp://csync@krikkit.galaxy.site:2222/home/csync</tt></pre>
|
|
</div></div>
|
|
<div class="para"><p>The remote destination is supported by plugins. By default csync ships with smb
|
|
and sftp support. For more information, see the manpage of <tt>csync(1)</tt>.</p></div>
|
|
<h3 id="_the_pam_module">4.3. The PAM module</h3><div style="clear:left"></div>
|
|
<div class="para"><p>pam_csync is a PAM module to provide roaming home directories for a user
|
|
session. This module is aimed at environments with central file servers a user
|
|
wishes to store his home directory. The Authentication Module verifies the
|
|
identity of a user and triggers a synchronization with the server on the first
|
|
login and the last logout. More information can be found in the manpage of the
|
|
module pam_csync(8).</p></div>
|
|
</div>
|
|
<h2 id="X90">5. Appendix A: Packager Notes</h2>
|
|
<div class="sectionbody">
|
|
<div class="para"><p>Read the <tt>README</tt>, <tt>INSTALL</tt> and <tt>FAQ</tt> files (in the distribution root
|
|
directory).</p></div>
|
|
</div>
|
|
<div id="footer">
|
|
<div id="footer-text">
|
|
Last updated 2008-12-23 10:15:54 CEST
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|