Meassure disk performance

This tutorial was tested on Slackware Linux only but should work for any other Unix with some minor changes in the iostat options. Keep in mind that some file systems (zfs, vxfs etc.) have their own tools to measure disk performance. In this case you should refer to them.
To meassure the disk performance of a specific disk use iostat - not dd. You can use dd to create some load but not to meassure the performance of a disk. The usage of iostat is very easy, a simple example for /dev/sdb could look like this: 

ps -eo in HP-UX

If you try to run something like:

# ps -eo ppid,pid,comm
...

Softraid with mdadm and Linux - Part I

Today I want you to show some basics about softraid with mdadm and Linux. This article features the following topics:

Creating RAID0
Creating and failing RAID1 (w/o spare disk)
Creating and failing RAID1 (w/ spare disk)
Creating and failing RAID01
Creating and failing RAID10