Softraid with mdadm and Linux - Part II

This is the second part of my mdadm tutorial. This part covers the following topics:

Creating and failing RAID5
Creating and failing RAID6
Converting from RAID1 to RAID10
Converting from RAID01 to RAID10

Extend dump devices in AIX

If you see a message in AIX like this:

LABEL:          DMPCHK_TOOSMALL
IDENTIFIER:     E87EF1BE

Date/Time:       Sun Jun  1 12:00:00 GMT+00:00 2012
Sequence Number: 182200
Machine Id:      XXXXXXXXXXXX
Node Id:         db03
Class:           O
Type:            PEND
WPAR:            Global
Resource Name:   dumpcheck

Description
The largest dump device is too small.

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

Remove carriage return ^M from a text file

Sometimes I have text files with a trailing carriage return character like this:

# vi file.txt
...
"foo"^M
"foo"^M
...

Creating empty files and using them as disks

If you ever needed some disks to test anything (eg. mdadm) then you can create your own harddisk in an existing filesystem. First create a 1GB file filled with zeros:

# dd if=/dev/zero of=/local/disk/vda bs=1 count=0 seek=1073741824

0+0 records in
0+0 records out
0 bytes (0 B) copied, 1.3252e-05 s, 0.0 kB/s

Accessing CD-ROM with FreeDOS

Today I decided to get my CD-ROM in FreeDOS running. As I have a nice old machine this was somekind tricky again. First I tried to load the uide caching driver:

C:\>devload uide.sys /D:CDROM01

...

XMS init error; UIDE not loaded!

...

Check CPU in FreeDOS

There are a lot of tools to get information and to measure the speed of your CPU, here is one which I think is compact and useful: CHKCPU    
It can be downloaded from http://web.inter.nl.net/hcc/J.Steunebrink/chkcpu.htm. Copy it to your FreeDOS machine and start it like this: 

Basic networking with FreeDOS

Setting up a network with FreeDOS can be a little bit frustrating when you don't know how to do it (just like me). Here is a short description how I installed my network under FreeDOS. I am using my old 386 again with a 3COM EtherLink III (3C509B) ISA NIC.