ZPOOL Mirror setup

What is the best setup for an zpool intended for database big inserts or TCP/IP dumps (i mean sustained high write throughput using 4 disks ?

I want buy 4 Wd RE4 2TB drives and get the more power i can !

i think of

zpool create tank mirror disk1 disk2 disk3 disk4

OR

zpool create tank mirror disk1 disk2 mirror disk3 disk4

OR

zpool create tank disk1 disk2 disk3 disk4

i think the solution with two mirror in a pool is the best, but not sure.

edit : ok so mirror IS RAID1. It is not possible to make this setup : RAID0 (RAID0, RAID0)

The three commands and ZFS setups you've listed are vastly different configurations.

zpool create tank mirror disk1 disk2 disk3 disk4

This creates a 4-way mirror with the capacity of ONE disk. Lots of protection, less space and less performance.
I don't think you want that.

zpool create tank mirror disk1 disk2 mirror disk3 disk4

This creates a stripe of two RAID 1 mirrors - RAID 1+0, with a capacity of TWO disks.
This is a good balance.

zpool create tank disk1 disk2 disk3 disk4

This creates a stripe of four disks - RAID 0, no protection against failure and a capacity of FOUR disks.
This is fast, but only make sense if you don't care about your data's integrity. If a drive fails, you will lose all of your data

Here's how mirror and striping work:

• If you want more write throughput, then more stripes
• If you want more fault tolerance and read performance, then more mirrors

So with 4 disks, the best way to achieve the most throughput without sacrificing fault tolerance is to create 2 mirrors, allowing the data to stripe over the mirrored pairs.

To take this further, if you had six disks, this configuration would give you more write performance:

zpool create tank mirror disk1 disk2 mirror disk3 disk4 mirror disk5 disk6

And this would give you more fault tolerance:

zpool create tank mirror disk1 disk2 disk3 mirror disk4 disk5 disk6