old-www/HOWTO/Flash-Memory-HOWTO/ext2.html

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> Setting up an Ext2 filesystem</TITLE
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></A
>8. Setting up an Ext2 filesystem</H1
><P
>&#13; The procedures described here will give the entire flash memory
device a single partition endowed with the ext2 filesystem. This
will make the device more suitable for use between Linux machines.
Don't do this if the device is supposed to operate between
Linux and Windows machines.
</P
><DIV
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><P
>&#13; The device associated with <TT
CLASS="filename"
>/dev/sda</TT
> will be
re-formatted. Any data present on it will be destroyed. To make
sure that the device you work with is the one intended, remove
similar devices from the USB-bus before starting these procedures.
</P
></TD
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></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="partition"
></A
>8.1. Partitioning</H2
><P
>&#13; It is assumed that the flash memory is mapped to <TT
CLASS="filename"
>&#13; /dev/sda</TT
>. In this section we treat the situation where
the whole flash memory device will become devoted to a single ext2
partition. In the example procedure shown below, a 128MB flash
memory was formatted for ext2. That is why figures like 131MB and
888 cylinders appear. The fdisk tool, which is used, simply reads
that from the device.
</P
><P
>
All operations are done by root. The single partition will be
created on <TT
CLASS="filename"
> /dev/sda</TT
>
(please note: not <TT
CLASS="filename"
>&#13; /dev/sda1</TT
> ) The procedure is described in a series of
steps with comments. The standard prompt of
<SPAN
CLASS="application"
>fdisk</SPAN
> is <TT
CLASS="prompt"
> Command (m for
help):</TT
> and you can, at any stage enter
<TT
CLASS="userinput"
><B
>m</B
></TT
> to see the available commands. If you do
that the result would be
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>&#13; Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
</PRE
></FONT
></TD
></TR
></TABLE
><P
>&#13; Your memory stick must be plugged in, but not mounted. Take care
that write protect is off.
</P
><P
> Here goes:</P
><TABLE
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><TD
><FONT
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><PRE
CLASS="screen"
>&#13; <TT
CLASS="prompt"
>#</TT
><TT
CLASS="userinput"
><B
><B
CLASS="command"
> fdisk</B
> /dev/sda</B
></TT
>
Command (m for help):<TT
CLASS="userinput"
><B
>d</B
></TT
> {enter }
Selected partition 1
Command (m for help):<TT
CLASS="userinput"
><B
>n</B
></TT
> {enter}
Command action
e extended
p primary partition (1-4)
<TT
CLASS="userinput"
><B
>p</B
></TT
> {enter}
Partition number (1-4):<TT
CLASS="userinput"
><B
>1</B
></TT
> {enter}
First cylinder (1-888, default 1): {press enter}
Using default value 1
Last cylinder ... (1-888, default 888): {press enter}
Using default value 888
</PRE
></FONT
></TD
></TR
></TABLE
><P
>
Now is a good time to verify that all went well by printing out
the partition details and table.
</P
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><TD
><FONT
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><PRE
CLASS="screen"
>&#13; Command (m for help): <TT
CLASS="userinput"
><B
>p</B
></TT
>
Disk /dev/sda: 131 MB, 131072000 bytes
9 heads, 32 sectors/track, 888 cylinders
Units = cylinders of 288 * 512 = 147456 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 888 127856 83 Linux
</PRE
></FONT
></TD
></TR
></TABLE
><P
>&#13; Make sure that the partition is not set up as bootable. There
should not be an asterisk under the heading "Boot" in the
partition table. Furthermore, the headings "Id" and "System"
should be as they are in the printout shown above. That indicates
that you can format the device in ext2 (next section). These are
the defaults. If they are not, they can be changed by
</P
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><PRE
CLASS="screen"
>&#13; Command (m for help): <TT
CLASS="userinput"
><B
>a</B
></TT
> [toggle a bootable flag]
Command (m for help): <TT
CLASS="userinput"
><B
>t</B
></TT
> [change a partition's system id]
</PRE
></FONT
></TD
></TR
></TABLE
><P
>
If (or when) the partition table is correct, you can conclude the
procedure with
</P
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><TD
><FONT
COLOR="#000000"
><PRE
CLASS="screen"
>&#13; Command (m for help): <TT
CLASS="userinput"
><B
>w</B
></TT
> [write table to disk and exit]
</PRE
></FONT
></TD
></TR
></TABLE
><P
> That's it!</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="making-ext2"
></A
>8.2. Making an ext2 device</H2
><P
>
Having completed the partition part, we go straight on to
"formatting" the device in ext2. For this we use the tool
mke2fs. This is straightforward.
</P
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CLASS="screen"
>&#13; <TT
CLASS="prompt"
>#</TT
> <TT
CLASS="userinput"
><B
><B
CLASS="command"
>mke2fs</B
> /dev/sda1</B
></TT
>
</PRE
></FONT
></TD
></TR
></TABLE
><P
>&#13; You might like to watch the led on your memory stick flicker
while this is happening. When it stops, the job is done.
</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="tests4"
></A
>8.3. Tests -- ext2</H2
><P
>
To see if you were successful, essentially repeat the procedures
described in <A
HREF="verifications.html#mounting"
>Section 7.3</A
> and <A
HREF="verifications.html#tests"
>Section 7.4</A
>
with two exceptions of detail. In the first place the mount
command should be
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>&#13; <TT
CLASS="prompt"
>#</TT
> <TT
CLASS="userinput"
><B
><B
CLASS="command"
>mount</B
> -t ext2 /dev/sda1 /mnt/memstick</B
></TT
>
</PRE
></FONT
></TD
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><P
>
The second exception is that the permissions on your favourite
text file should not change anymore.
</P
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