239 lines
4.0 KiB
HTML
239 lines
4.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Disks without filesystems</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Linux System Administrators Guide"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Using Disks and Other Storage Media"
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HREF="disk-usage.html"><LINK
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REL="PREVIOUS"
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TITLE="Filesystems"
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HREF="filesystems.html"><LINK
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REL="NEXT"
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TITLE="Allocating disk space"
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HREF="alloc-disk.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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SUMMARY="Header navigation table"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux System Administrators Guide: </TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="filesystems.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 5. Using Disks and Other Storage Media</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="alloc-disk.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="DISK-NO-FS"
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></A
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>5.11. Disks without filesystems</H1
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><P
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>Not all disks or partitions are used as filesystems.
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A swap partition, for example, will not have a filesystem on it.
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Many floppies are used in a tape-drive emulating fashion, so that a
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<B
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CLASS="COMMAND"
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>tar</B
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> (tape archive) or other file is written
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directly on the raw disk, without a filesystem. Linux boot floppies
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don't
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contain a filesystem, only the raw kernel.</P
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><P
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>Avoiding a filesystem has the advantage of making more of
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the disk usable, since a filesystem always has some bookkeeping
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overhead. It also makes the disks more easily compatible with other
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systems: for example, the <B
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CLASS="COMMAND"
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>tar</B
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> file format is the
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same on all systems, while filesystems are different on most
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systems. You will quickly get used to disks without filesystems if
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you need them. Bootable Linux floppies
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also do not necessarily have a filesystem, although they may.</P
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><P
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>One reason to use raw disks is to make image copies of them.
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For instance, if the disk contains a partially damaged filesystem,
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it is a good idea to make an exact copy of it before trying to fix
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it, since then you can start again if your fixing breaks things even
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more. One way to do this is to use <B
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CLASS="COMMAND"
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>dd</B
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>:
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<TABLE
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BORDER="1"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="SCREEN"
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> <TT
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CLASS="PROMPT"
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>$</TT
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> <TT
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CLASS="USERINPUT"
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><B
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>dd if=/dev/fd0H1440
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of=floppy-image</B
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></TT
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>
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<TT
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CLASS="COMPUTEROUTPUT"
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>2880+0 records in
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2880+0 records out</TT
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>
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<TT
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CLASS="PROMPT"
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>$</TT
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> <TT
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CLASS="USERINPUT"
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><B
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>dd if=floppy-image
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of=/dev/fd0H1440</B
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></TT
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>
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<TT
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CLASS="COMPUTEROUTPUT"
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>2880+0 records in
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2880+0 records out</TT
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>
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<TT
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CLASS="PROMPT"
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>$</TT
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>
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</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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The first <B
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CLASS="COMMAND"
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>dd</B
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> makes an exact image of the floppy
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to the file <TT
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CLASS="FILENAME"
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>floppy-image</TT
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>, the second one writes
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the image to the floppy. (The user has presumably switched the
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floppy before the second command. Otherwise the
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command pair is of doubtful usefulness.)</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="filesystems.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="alloc-disk.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>Filesystems</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="disk-usage.html"
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>Allocating disk space</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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> |