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| author | James Meyer <jams@linhes.org> | 2010-12-04 23:44:45 (GMT) |
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| committer | James Meyer <jams@linhes.org> | 2010-12-04 23:44:51 (GMT) |
| commit | f51fb708846d13222bd97b3f760eb3be902c0be0 (patch) | |
| tree | ad25ff81828f12cb7da86384863e163cb4e001f2 /build_tools/clarch/larch/docs/html/larch_sessionsave.html | |
| parent | 4384efe238cdfeac86fae0d8e1097a409350f8c6 (diff) | |
| download | linhes_dev-f51fb708846d13222bd97b3f760eb3be902c0be0.zip | |
remove old versions of larch 6 and 7
Diffstat (limited to 'build_tools/clarch/larch/docs/html/larch_sessionsave.html')
| -rw-r--r-- | build_tools/clarch/larch/docs/html/larch_sessionsave.html | 162 |
1 files changed, 0 insertions, 162 deletions
diff --git a/build_tools/clarch/larch/docs/html/larch_sessionsave.html b/build_tools/clarch/larch/docs/html/larch_sessionsave.html deleted file mode 100644 index edca50c..0000000 --- a/build_tools/clarch/larch/docs/html/larch_sessionsave.html +++ /dev/null @@ -1,162 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> -<html> - -<head> - <meta content="text/html;charset=UTF-8" http-equiv="Content-Type" /> - <title>larch session saving</title> - <meta content="gradgrind" name="author" /> -</head> - -<body> - -<table style="text-align: left; width: 100%;" border="1" cellpadding="2" cellspacing="2"> - <tbody> - <tr> - <td><a href="larch_fstab.html">Previous: /etc/fstab</a></td> - - <td><a href="larch_docindex.html">Table of Contents</a></td> - - <td><a href="larch_ssh.html">Next: ssh access</a></td> - </tr> - </tbody> -</table> - -<br /> - -<h1><big>larch</big> – a do-it-yourself live <em>Arch Linux</em> CD</h1> - -<img style="border: 0px solid ; width: 320px; height: 320px;" alt="" src="larch1.jpg" - name="graphics1" align="right" hspace="10" vspace="10" /> -<br /><br /> - -<h2>Saving a session back to the boot device (or even somewhere else)</h2> - -<p>An easy way to create a customized live-USB-stick is to start from an -existing one, make whatever changes you like, and then save the result back to -the USB-stick. -</p> - -<h3><a name="overlays"></a>Overlay archives, <strong>overlay.ovl</strong> and -<strong>mods.sqf</strong></h3> - -<p>In <em>larch</em> the <em>overlay</em> file-system (in the -<em>compressed</em> file 'overlay.ovl') can be rebuilt -from the state of the live system when it shuts down. -This is handled primarily by the script <strong>/opt/larch-live/session-save/saveovl</strong>, which is -called from the customized shutdown function. -If the medium is writable and contains a file 'larch/save', the user is offered the possibility of -rewriting the overlay archive, thus saving the current state. -</p> - -<p>The main overlay archive (<strong>overlay.ovl</strong>) is unpacked into memory -at boot and repacked when saving the session at shutdown. 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 into the middle <em>union</em> layer in <strong>mods.sqf</strong> (which is -normally not copied to memory), thus restoring the rapid load and save times -for <strong>overlay.ovl</strong>, and maximizing the available memory. I call this process -'overlay merging', and it is offered as a shutdown option. -It takes longer to execute than a normal session save, but from larch version 5.2 -a new <em>aufs</em> option allows the merging to be done quicker than it was -previously and without significant extra memory requirements. In this version -a separate <em>aufs</em> union of the two overlay layers is mounted in which -the whiteouts are visible. This union can then be squashed directly, without -requiring the new, merged overlay to be rebuilt in memory. As it is a feature -of <em>aufs</em>, overlay merging is no longer supported for <em>unionfs</em> -(note that <em>unionfs</em> is at present not actively supported in <em>larch</em> -anyway). -</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 should be possible to include package addition and removal in the list -of customizations undertaken using this method, but there are some limitations. Apart from -size considerations (the top level overlay is unpacked into memory at boot), there is also -a limitation connected with the kernel. Essentially, the kernel and its modules may not -be updated. <strong>If you do this, you may well make a mess of your system</strong>. -In other words, be very careful with 'pacman -Su' - only upgrade selected packages. -</p> -<p>The reason for this is that the kernel is not contained within the -squashed file-system, but is held separately on the boot medium, while its modules -are contained in the squashed system and also in the initramfs. Updating these is not -impossible (if booting from a writable medium), but <em>pacman</em> cannot do it and -it is not straightforward (e.g. using a CD to boot to a USB-stick on a computer not -supporting USB boot would additionally need a new CD). A complete rebuild of the live -system might be a better approach. And using 'larchify' it should even be possible to -perform such a rebuild from within the running live system. -</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. -</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</em> live 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>larch</em> live system. -</p> -<ul> - <li><strong>session-save</strong> - <p>Used in <strong>/opt/larch-live/session-save/saveovl</strong>. 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.ovl' on the boot medium. - </p> - </li> - <li><strong>save-menu</strong> - <p>Used in <strong>/opt/larch-live/session-save/saveovl</strong>. 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-save</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><strong>merge-adjust</strong> - <p>Used in <strong>/opt/larch-live/session-save/merge_overlay</strong>. This script can be - used to further customize aspects of the overlay merging process. Note that if the - <strong>session-save</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><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> - -<table style="text-align: left; width: 100%;" border="1" cellpadding="2" cellspacing="2"> - <tbody> - <tr> - <td><a href="larch_fstab.html">Previous: /etc/fstab</a></td> - - <td><a href="larch_docindex.html">Table of Contents</a></td> - - <td><a href="larch_ssh.html">Next: ssh access</a></td> - </tr> - </tbody> -</table> - -</body> -</html> |