diff options
Diffstat (limited to 'build_tools/l7/larch0/docs/html/larch_sessionsave.html')
| -rw-r--r-- | build_tools/l7/larch0/docs/html/larch_sessionsave.html | 191 |
1 files changed, 0 insertions, 191 deletions
diff --git a/build_tools/l7/larch0/docs/html/larch_sessionsave.html b/build_tools/l7/larch0/docs/html/larch_sessionsave.html deleted file mode 100644 index 2f2ca95..0000000 --- a/build_tools/l7/larch0/docs/html/larch_sessionsave.html +++ /dev/null @@ -1,191 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/xhtml1-strict.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> - -<html> -<head> -<meta http-equiv="Content-type" content="text/html; charset=utf-8" /> -<title>Saving a session back to the boot device (or even somewhere else)</title> -<!-- (en) Add your meta data here --> - -<link href="css/larchdocs.css" rel="stylesheet" type="text/css"/> -<!--[if lte IE 7]> -<link href="css/yaml/core/iehacks.css" rel="stylesheet" type="text/css" /> -<![endif]--> -</head> - -<body> -<!-- skip link navigation --> -<ul id="skiplinks"> - <li><a class="skip" href="#col1">Skip to main content (Press Enter).</a></li> -</ul> - -<div class="page_margins"> - <div class="page"> - <div id="top"><div id="tm"></div></div> - <!-- begin: #col1 --> - <div id="col1" role="main"> - <div id="col1_content"> - <div id="header" role="banner"> - <h1><span><em>live Arch Linux</em> builder</span></h1> - </div> - - <!-- begin: #col3 navigation column --> - <div id="col3" role="complementary"> - <div id="col3_content"> - <img class="indent2" alt="larch logo" src="css/screen/larch150x.png" width="150" height="150" /> - <div class="vlist"> - <ul> - <li><a href="index.html"><h6>Table Of Contents</h6></a></li> - <li><a href="larch_ssh.html"><h6>Next:</h6> - <div class="indent1">ssh access</div></a></li> - <li><a href="larch_live_system.html"><h6>Previous:</h6> - <div class="indent1">Structure of a larch live system</div></a></li> - </ul> - </div> - </div> - </div> - <!-- end: #col3 --> - -<div class="larchdocs"> -<h2 id="pagetitle" level="1">Saving a session back to the boot device (or even somewhere else)</h2> - -<p>An easy way to create a customized <em>live</em> system is to start from an -existing one, make whatever changes you like, and then save the result back to -the boot device. Of course, for this you need a writeable boot device, e.g. -a USB-stick. -</p> - -<h3><a name="overlays"></a>Overlay archives</h3> - -<p>In <em>larch</em> the uppermost layer in the union file-system is in -<em>tmpfs</em> and can (optionally) be saved at shutdown to the boot medium. -It is <em>compressed</em> using <em>tar</em> and <em>lzop</em> to the file -'overlay.tar.lzo'. When the system next boots this file will then be -unpacked into the initially empty top layer. -</p> - -<p>This is handled primarily by the 'shutdown2' script, supplied in the -'larch-live' package. It is called from a hook function in 'etc/rc.shutdown'. -If the medium is writeable and contains a file 'larch/save', the user is -offered the possibility of saving this overlay archive, thus saving the -current state. -</p> - -<p>When this archive grows too large it will reduce the amount of available -memory, perhaps to an unacceptable extent. -It will also lengthen boot and shutdown times. -To counter this, it is possible to merge the -overlay archive with the middle (<em>squashfs</em>) <em>union</em> layer, -<strong>mods.sqf</strong> (which is normally not copied to memory), -thus restoring the rapid load and save times for <strong>overlay.tar.lzo</strong>, -and maximizing the available memory. I call this process -'overlay merging', and it is offered as a shutdown option. The script -'merge_overlay' (in the 'larch-live' package) provides this facility. -It takes longer to execute than a normal session save, so it should probably -not be used for every session saving operation, but just when the top overlay -gets too big. Note that use of the overlay merging feature creates an -additional layer in the <em>union</em>, 'filter.sqf'. This contains only -'whiteout' files to cover up overwritten data in the underlying 'system.sqf'. -Unlike in previous <em>larch</em> versions the 'mods.sqf' archive contains -no 'whiteouts'. It is hoped that this new structure will cure the -problems experienced in these earlier versions. -</p> - -<h3><a name="var_files"></a>Special places in /var</h3> - -<p>It was considered undesirable to include some things in the '/var' directory -in the session saves, primarily because of the space they occupy. Firstly, -the standard <em>pacman</em> package cache, '/var/cache/pacman/pkg' - if you -do want to save your cache, you should either handle this manually or set -up another location using 'CacheDir' in /etc/pacman.conf'. Also the log files -(in '/var/log') and '/var/tmp' (temporary files, like '/tmp') are not saved. -</p> - -<h3><a name="upd_packages"></a>Updating packages</h3> - -<p>It is possible to perform package addition and removal in the <em>live</em> -system, but one should be aware that packages in the base system are not actually -replaced, just (effectively) hidden, so that the space usage might become a -consideration. Also the handling of kernel updates must be handled in a special -way, because it is stored outside the root file-system, on the boot medium -and needs a separate mechanism to save it at shutdown. It should be fairly -transparent to the user, but under certain circumstances it might be necessary -to bear this in mind. -</p> - -<p>At some point, after extensive updating, it might be desirable to completely -<a href="larch_rebuild.html">rebuild the system</a>, so that also -'system.sqf' is recreated. This will require quite a bit of space, -but should otherwise pose no great problems. -</p> - -<h3><a name="de-Act"></a>Activating and deactivating the session-saving feature</h3> - -<p>As mentioned above, for this feature to be available, there must be a -file with the name 'save' in the boot medium's 'larch' directory. This -will be generated automatically if installing to a partition (i.e. if not -building an <em>iso</em>) and if there is no 'nosave' file in the profile. -The gui provides a button to create and delete this 'nosave' file, -thus disabling or enabling session saving on the created medium. -</p> - -<h3><a name="custom"></a>Customizing the behaviour using scripts</h3> - -<p>Some aspects of the session saving can be customized by writing scripts to -override the default behaviour. These scripts are (in general) kept on the boot -medium, in the 'larch' directory. As these are shell scripts and their use requires -some knowledge of the inner workings of the <em>larch live </em>system, it will -almost certainly be necessary to read the existing <em>larch</em> scripts where the -custom scripts are 'sourced' if you want to -write your own scripts to change the behaviour of the <em>live</em> system in -this respect. All these scripts are found in the 'larch-live' package. -</p> -<ul> - <li><strong>session-save0</strong> - <p>Used in <strong>session-save/shutdown2</strong> (in function 'checkse'). - This script can be used to customize the creation of the new overlay - archive, e.g. by specifying a new location. The default is - 'overlay.tar.lzo' on the boot medium. - </p> - </li> - <li><strong>save-menu</strong> - <p>Used in <strong>session-save/shutdown2</strong> (in function - 'session-save'). This script can be used to further customize the creation - of the new overlay archive, e.g. by providing an alternative session save - menu. Note that if the <strong>session-save0</strong> script specified - an alternative device path for saving the overlay, this script will be - sought in the 'larch' directory on that path. - </p> - </li> - <li><a name="boot-init"></a><strong>boot-init</strong> - <p>In initramfs hook <strong>larch3</strong>. This script allows adjustment of - the overlay handling during the boot process, e.g. getting them from another - path. - Note that the shell environment here is that of the initramfs and thus - very limited. - </p> - </li> -</ul> - -</div> - - - <div class="topref"><a href="#top">Top</a></div> - </div> - <!-- begin: #footer --> - <div id="footer"> - <div id="footer-content" role="contentinfo">© 2010 Michael Towers<br /> - Page layout assisted by <a href="http://www.yaml.de/">YAML</a> and - <a href="http://www.kuwata-lab.com/tenjin/">pyTenjin</a> - </div> - </div> - <!-- end: #footer --> - </div> - <!-- end: #col1 --> - <div id="bottom"><div id="bl"><div id="bm"></div></div></div> - </div> -</div> -<!-- full skiplink functionality in webkit browsers --> -<script src="css/yaml/core/js/webkit-focusfix.js" type="text/javascript"></script> -</body> -</html> |