HOWTO: Multi Disk System Tuning: Appendix J: Example IV: Server with 4 Drives

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## 30. Appendix J: Example IV: Server with 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.

> `

>     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

> `

Setup is optimised with respect to track positioning but also for minimising drive seeks.

If you want DOS or Windows too you will have to use `sda1` for this and move the other partitions after that. It will be advantageous to use the swap partitions on `sdb2`, `sdc2` and `sdd2` for Windows swap, `TEMPDIR` and Windows temporary directory under these sessions. A number of other HOWTOs describe how you can make several operating systems coexist on your machine.

For completeness a 4 drive example using several types of RAID is also given which is even more complex than the example above.

> `

>     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

> `

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.

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.

With such a complicated comes an equally complicated `fstab` file. The large number of partitions makes it important to do the `fsck` passes in the right order, otherwise the process can take perhaps ten times as long time to complete as the optimal solution.

> `

>     /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)

> `

The letters in the brackets indicate what drives will be active for each `fsck` entry and pass. These letters are not present in a real `fstab` file. All in all there are 7 passes.

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