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<TITLE>HOWTO: Multi Disk System Tuning: Appendix J: Example IV: Server with 4 Drives</TITLE>
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<H2><A NAME="s30">30. Appendix J: Example IV: Server with 4 Drives</A></H2>
<P>
<!--
disk!example!server, 4 drives
-->
This gives an example of using all techniques described earlier, short of
RAID. It is admittedly rather complicated but offers in return high
performance from modest hardware. Dimensioning are skipped but reasonable
figures can be found in previous examples.
<P>
<BLOCKQUOTE><CODE>
<PRE>
Partition sda sdb sdc sdd
---- ---- ---- ----
1 root overview lib news
2 swap swap swap swap
3 home /usr /var/tmp /tmp
4 spare root mail /var
</PRE>
</CODE></BLOCKQUOTE>
<P>Setup is optimised with respect to track positioning but also for
minimising drive seeks.
<P>If you want DOS or Windows too you will have to use <CODE>sda1</CODE> for this
and move the other partitions after that. It will be advantageous to
use the swap partitions on <CODE>sdb2</CODE>, <CODE>sdc2</CODE> and <CODE>sdd2</CODE> for
Windows swap, <CODE>TEMPDIR</CODE> and Windows temporary directory under these
sessions. A number of other HOWTOs describe how you can make several
operating systems coexist on your machine.
<P>
<P>For completeness a 4 drive example using several types of RAID is
also given which is even more complex than the example above.
<P>
<BLOCKQUOTE><CODE>
<PRE>
Partition sda sdb sdc sdd
---- ---- ---- ----
1 boot overview news news
2 overview swap swap swap
3 swap lib lib lib
4 lib overview /tmp /tmp
5 /var/tmp /var/tmp mail /usr
6 /home /usr /usr mail
7 /usr /home /var
8 / (root) spare root
</PRE>
</CODE></BLOCKQUOTE>
<P>Here all duplicates are parts of a RAID 0 set with two exceptions,
swap which is interleaved and home and mail which are implemented
as RAID 1 for safety.
<P>Note that boot and root are separated: only the boot file with the
kernel has to reside within the 1023 cylinder limit. The rest of the
root files can be anywhere and here they are placed on the slowest
outermost partition. For simplicity and safety the root partition
is not on a RAID system.
<P>With such a complicated comes an equally complicated <CODE>fstab</CODE> file.
The large number of partitions makes it important to do the <CODE>fsck</CODE>
passes in the right order, otherwise the process can take perhaps
ten times as long time to complete as the optimal solution.
<P>
<BLOCKQUOTE><CODE>
<PRE>
/dev/sda8 / ? ? 1 1 (a)
/dev/sdb8 / ? noauto 1 2 (b)
/dev/sda1 boot ? ? 1 2 (a)
/dev/sdc7 /var ? ? 1 2 (c)
/dev/md1 news ? ? 1 3 (c+d)
/dev/md2 /var/tmp ? ? 1 3 (a+b)
/dev/md3 mail ? ? 1 4 (c+d)
/dev/md4 /home ? ? 1 4 (a+b)
/dev/md5 /tmp ? ? 1 5 (c+d)
/dev/md6 /usr ? ? 1 6 (a+b+c+d)
/dev/md7 /lib ? ? 1 7 (a+b+c+d)
</PRE>
</CODE></BLOCKQUOTE>
<P>The letters in the brackets indicate what drives will be active
for each <CODE>fsck</CODE> entry and pass. These letters are <EM>not</EM> present
in a real <CODE>fstab</CODE> file.
All in all there are 7 passes.
<P>
<P>
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