Basically, the system works like this: Instead of putting the actual files in your file system, we have made transparent virtual links to them, thereby conserving a significant amount of disk space for you.

When you write a directory or file, the link is transparently replaced with a regular directory or file that is written to your disk and counts against your disk space allocation.

An example of this is if you edited the /usr/local/etc/sudoers file. Each directory in that path plus the sudoers file is written to your disk space. All the unmodified files within each of those directories remained as virtual links.

Freedom and Responsibility
Your VPS v2 Virtual Server gives you almost unlimited freedom in configuring the server any way you want. And while the ability is yours to reconfigure the server, so is the responsibility for doing so. You will be responsible for updating, patching, and maintaining the security of your server for any customization that you do. This ability is explained in the following example, using Apache.

Suppose you do not want Apache updates.

A freeze on the directory containing the program prevents each directory in that path from being updated.

Relink compares checksums on every file in the directory path, “collapses” those files and directories whose checksums are equal to the directories and files in /skel, and relinks them. Because the httpd.conf file is different, relink cannot “collapse” /usr/local/apache/conf. Modified files cannot be relinked.

Now that relink has worked its magic, you now no longer own the directories and files that were on your disk, counting against your allocation. See the relink man page for more information.

Support Limits
If you choose to make a major configuration change such as the previous example of Apache, the responsibility for maintaining that part of your server is solely yours and falls outside our support limits.

If you decide you would rather make your present configuration current with that of the file system in /skel and perform the thaw and relink operations on the modified directories and files, you will again be within our support limits.

The longer you go on your own, the more changes are made to the filesystem in /skel. It will eventually become impossible to reconcile the checksums on the two file systems—yours and /skel’s. If that occurs, you will be permanently on your own.

Important Commands, Directories, and Files
The following table describes commands and directories used to manipulate directories and files in the VPS v2 Virtual Server file system.

Name	Type	Description
touch (directory/or/file)	UNIX command	Updates the access and modification times; useful in forcing other commands to handle files in a certain way.
freeze (directory/or/file)	command	Writes the affected directories and files to the virtual disk and flags them with a “frozen” status so they cannot be overwritten by /skel.
thaw (directory/or/file)	command	Removes the “frozen” status on files.
relink (directory/or/file)	command	Runs a checksum comparison between /skel and the virtual file system
vunlink directory/path/to/file	command	Unlinks a virtual directory hierarchy (dir)  vunlink /usr/local/foo (file) vunlink/usr/local/foo/misc.file
/skel	directory	Contains a copy of the files system of a pristine VPS v2 Virtual Server.

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