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<H2><A NAME="SECTION005810000000000000000">Other tools for the ext2 filesystem</A></H2>
<P>
In addition to the filesystem creator (<tt>mke2fs</tt><A NAME="1740"> </A>) and
checker (<tt>e2fsck</tt><A NAME="1742"> </A>) accessible directly or via the
filesystem type independent front ends, the ext2
filesystem has some additional tools that can be useful.
<P>
<tt>tune2fs</tt><A NAME="1744"> </A> adjusts filesystem parameters. Some of the
more interesting parameters are:
<UL>
<LI> A maximal mount count. <tt>e2fsck</tt><A NAME="1746"> </A> enforces a check when
filesystem has been mounted too many times, even if
the clean flag is set. For a system that is used for
developing or testing the system, it might be a good
idea to reduce this limit.
<LI> A maximal time between checks. <tt>e2fsck</tt><A NAME="1748"> </A> can also enforce
a maximal time between two checks, even if the clean
flag is set, and the filesystem hasn't been mounted very
often. This can be disabled, however.
<LI> Number of blocks reserved for <tt>root</tt>. Ext2
reserves some blocks for <tt>root</tt> so that if the
filesystem fills up, it is still possible to do system
administration without having to delete anything. The
reserved amount is by default 5%, which on most disks
isn't enough to be wasteful. However, for floppies there
is no point in reserving any blocks.
</UL>
See the <em>tune2fs</em><A NAME="1750"> </A> manual page for more information.
<P>
<tt>dumpe2fs</tt><A NAME="1752"> </A> shows information about an ext2 filesystem, mostly
from the superblock. Figure <A HREF="node51.html#figdumpe2fsoutput">4.5</A> shows
a sample output. Some of the information in the output is
technical and requires understanding of how the filesystem
works (see appendix <A HREF="#chapext2fspaper"><IMG ALIGN=BOTTOM ALT="gif" SRC="./cross_ref_motif.gif"></A>), but much of
it is readily understandable even for layadmins.
<P>
<P><A NAME="1434"> </A><A NAME="figdumpe2fsoutput"> </A><IMG WIDTH=421 HEIGHT=569 ALIGN=BOTTOM ALT="figure1374" SRC="img9.gif"><BR>
<STRONG>Figure 4.5:</STRONG> Sample output from <tt>dumpe2fs</tt><A NAME="1754"> </A><BR>
<P>
<P>
<tt>debugfs</tt><A NAME="1756"> </A> is a filesystem debugger. It allows direct
access to the filesystem data structures stored on disk and
can thus be used to repair a disk that is so broken that
<tt>fsck</tt><A NAME="1758"> </A> can't fix it automatically. It has also been known
to be used to recover deleted files. However, <tt>debugfs</tt><A NAME="1760"> </A>
very much requires that you understand what you're doing;
a failure to understand can destroy all your data.
<P>
<tt>dump</tt><A NAME="1762"> </A> and <tt>restore</tt><A NAME="1764"> </A> can be used to back up an
ext2 filesystem. They are ext2 specific versions of the
traditional UNIX backup tools. See chapter <A HREF="node96.html#chapbackups">10</A>
for more information on backups.
<P>
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<P><ADDRESS>
<I>Lars Wirzenius <BR>
Sat Nov 15 02:32:11 EET 1997</I>
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