NAS Build (HDD and SSD question)

[emieldegroot]

I am confused buying the 'right' HDD for my new server / nas. I am looking for five or six 3tb devices:

5200 RPM:
Hitachi Deskstar 5K3000 or Seagate Barracuda ST3000DM001
The Seagate cost less (€20-€40 per unit) but is there a significant difference between those two?

7200 RPM
I can buy second hand Seagate Barracuda XT (3 unites) and Hitachi Deskstar 7K3000 (3 units) for the same price as 6x Seagate Barracuda ST3000DM001(new). But what about preformance when i mix different types of HDD's. Is this possible in ZFS and will it downgrade my speed? Then again, maybe 7200 is too much for a server and i should stick with 5200.

To give some background information of my (planned) server

The server will run esxi (ZFSguru for ZFS with sabnzbd, sickbeard; 4 VM's and a musicserver (logitech squeezebox). I am stuck with mITX (space issue). I was thinking of the following components:
Intel Desktop Board DQ67EPB3
Intel Core i5 2500
Scythe Big Shuriken 2 Rev. B
16gb: GeIL Black Dragon GB316GB1333C9DC
Crucial m4 CT128M4SSD2 128GB
IBM M1015 (IT firmware)
be quiet! Straight Power E9 400W (Gold)
Lian Li PC-Q25B

I also have another question: i can buy 2x agility OCZ Agility 3 SATA III 120 GB (run as raid 0) for the same price as 1x Crucial m4. Should i go for the Agility 3 instead of M4?

 

[emieldegroot]

Mixing HDD from the same size for me is the 'cheapest' option. I was thinking of 2x Hitachi Deskstar 5K3000 3tb + 3x Seagate Barracuda ST3000DM001 in zfs pool. Will this give preformance issues?

 

[Aesma]

New Seagate means one year warranty only.

 

[emieldegroot]

So Hitachi it is

 

[emieldegroot]

Also found a benchmark between the two

Other then the warrenty, the seagate preformance is better then hitachi. Power use is better for hitachi altough they are close together....after the benchmark still in doubt. Any suggestions?