Non-optimal RAIDZ2 vs RAIDZ1 + Spare

[IonutZ]

So I finally got all the hardware, threw it together, the FreeNAS GUI looks beautiful haha. I appreciate the craftsmanship of the application since I'm a business analyst working in IT on webapps.

I went to create my first ZFS volume and I found out that running RAIDZ2 is non-optimal. I have 5x 4TB drives. I was wondering why this is non-optimal? Also... would it be more optimal to create a RAIDZ1 with 4 drives and keep 1 as a spare? Which one of the two options is better to go with?

Would 6 drives run an optimal RAIDZ2 config?

Also, I vaguely recall you can add drives (Vdevs) to a zpool... from cyberjock's powerpoint presentation. In the event I go with the RAIDZ2 on 5 drives, will I be able to make it a 6 drive without any problems?

Thank you!

 

[cyberjock]

Nope. From my presentation:

¨You cannot add more hard drives to a VDev once it is created.*

The underline is from the presentation.

 

[IonutZ]

Ok, fair enough haha, I'll go over your guide again. Any input on which config to go with though?

 

[gpsguy]

Yes.

Buy another 4Tb drive and go with RAIDz2 from the get go.

Would 6 drives run an optimal RAIDZ2 config?

 

[cyberjock]

OOps... what gpsguy said. Go with 6 drive RAIDZ2. it's optimal, even though "optimal" doesn't mean much with compression. :P

 

[IonutZ]

Done... gotta wait 3 more days now ._. lol in the mean time, I wanna play around with a 5x drive RAIDZ2. Is there a good way to benchmark read/write speed? Do what's written in the sticky right above this thread?