Real world performance hit from 5 disk Z2?

[bcrowder]

I've searched and been reading through all the threads. I don't see anything other then it's not recommended. Can anyone expand on what my REAL WORLD performance hit would be using 5 vs 6 Seagate ST1500DL003 1.5 TB drives in ZFS 2? If it's only a 5 or 10% loss in performance, I wouldn't care. Adding a new pool and would like to use Z2 but am limited to 5 drives.

Thanks,
Bill

 

[bcrowder]

This seems important to those working with in a budget or hardware constraints, any answers?

 

[ProtoSD]

I have a 5 disk z2 pool running on an Atom with 8G of RAM and it runs great. Sorry I can't offer any numbers off the top of my head, but I posted them in other threads.

The only reason I went with 5 instead of 6 disks is because I wanted a spare SATA port open so I could hook up drives to either import data or back it up. Other than loosing the space I'd get from having a 6 disk pool, I can't really complain about the performance.

 

[bcrowder]

Thanks for the quick reply. Wasn't looking for numbers, the runs great works for me. Keep up the good work on this forum, it is appreciated.

Thanks,
Bill

 

[cyberjock]

Honestly, giving a value for how much of a performance hit you take from a Z2 pool is hard to quantify. It depends on alot of things. If you only have 4GB of RAM, you may have problems. If you have a very slow CPU, it could affect performance.

Also, as a consideration, what you define as a performance hit may not matter. For example if you plan to have a single gigabit LAN connection and your zpool is only 200MB/sec instead of 600MB/sec(which is a 66% performance hit.. could be considered major) you are still far above what gigabit provides. The performance hit, while numerically is significant, you'd never be able to see with gigabit. Now if you are running 10 gigabit, that's a different story.

There is no answer to your question.

 

[bcrowder]

Nobsause80, you just answered my question... :)

 

[bcrowder]

Ok, build complete, two zpools one is 5 1.5tb drives in Z2 and the other is 3 older 1tb drives in Z1. Have not had time to test it, completely but I'm very happy with the results. Getting 40 to 50 write and 80 to 100 read.

Thanks Proto for the tweeks you posted on another thread.

Thanks Noobsause80, "The performance hit, while numerically is significant, you'd never be able to see with gigabit. Now if you are running 10 gigabit, that's a different story." that's exactly what I wanted to know. There is an answer to that question.


RAIDMAX Tornado with ISTARUSA Drive Cage
AMD Athlon II X2 240 Regar
8G DDR2 800
LSI 9211-8i Flashed IT
5 Recetified Seagate ST1500DL003 1.5TB drives in Z2
3 Old 1TB drives in Z1

 

[bcrowder]

Second observation for those reading, the 3 older Sata II drives in the Z1 array is getting half the write rates as the newer drives in the Z2 array. Hmm...