LinuxQuestions.org - Setup RAID 5 + 1 spare disk

I want to build a 6xSATA RAID 5 system with on of the disks as spare disk. I think this give me a chance of 2 of 6 disks failing without losing data. I am right?

Hardware: Intel ICH10R

First I will creat a 3xSATA RAID 5, after I will add the spare disk and after that I will add the others disks.

This is what I think I should do.

Step 1:

Create RAID Device

Code:

mdadm --create --verbose /dev/md0 --metadata 1.2 --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1

I read that "--metadata 1.2" is the best option. It is true?

Create filesystem on the RAID device

Using this method of calculation:

* chunk size = 128kB (for RAID 5)
* block size = 4kB (recommended for large files, and most of time)
* stride = chunk / block = 128kB / 4k = 32kB
* stripe-width = stride * ( (n disks in raid5) - 1 ) = 32kB * ( (5)- 1 ) = 32kB * 4 = 128kb

Then:

Code:

mkfs.ext3 -v -m .1 -b 4096 -E stride=32,stripe-width=128 /dev/md0

Step 2:

Add spare-disk

Code:

mdadm --add /dev/md0 /dev/sdd1

Is this enough?

Step 3:

Adding disks:

Code:

mdadm --add /dev/md0 /dev/sde1

mdadm --grow /dev/md0 --raid-devices=4



fsck.ext3 /dev/md0

resize2fs /dev/md0

Any help will be useful.
Thanks!