How to grow software raid in Ubuntu.

This is rather a memo for me than real article, cause there are a lot of tutorials about growing raid.
I grow soft raid on average every 6 months, so I tend to forget all the necessary steps.

This time I've grown my 3TB raid5 to 4.5TB raid5 adding 1 disk to raid set under Ubuntu 10.04.

First thing after installing new disk in the computer is copying partition table from one of raid disks to new one. Sfdisk is the best tool to do this.

sfdisk -d /dev/sda > sda.part
sfdisk -f /dev/sdd < sda.part

Linux software raid with 2-6 disks ext3/ext4 performance tests.

Lately I've got 6 500GB SATA 7200 rpm disks in my hands. So I decided to do some performance tests of linux software raid.
There are a lot of legends about raid levels, which are better for database or file storing. Also there are informations how much which raid layout loads CPU.
So I decided to verify those.

Ext3 / ext4 extended options with soft raid and simple performance tests.

I guess almost every linux admin heard that when you creating ext filesystem over software raid you should consider using extended mkfs options. Two important options for that operation are: stride and stipe-width, which you should calculate for your setup of raid (number of disks, level, chunk size). You can calculate all those parameters each time you create ext2/ext3/ext4, but there are lot of ready calculators to use. I'd prefer using this one. Cause it's simple and fast.

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by Dr. Radut