by JoKeru

Chunk size, stride size, stripe size, ext4, alignment ...

In order to get the best performance from your RAID storage, you need to align everything (the filesystem with your RAID setup)!

1 - chunk size of raid array - how you choose this value is not under this post's scope, let's consider the default for my raid controller - 256k

2 - filesystem block size (ext4) is set to default - 4k

3 - filesystem stride = array chunk size / filesystem block size: 256k / 4k = 64k

4 - filesystem stripe-width = filesystem stride * number of data disks in array (for a raid5 with 4 disks, this will be 3): 64k * 3 = 192k

So this will translate into:

$ mkfs.ext4 -b 4096 -E stride=64 -E stripe-width=64 /dev/sdb

Or if you're too lazy to do the math, you can use this online calculator: