When to go z3?

[foxhunt]

Trying to figure if freenas z2 10x8TB is safe enough or maybe go z3 12x8TB? I've got 10 drives but to maximize the array I can pick-up a few more drives while they are on sale.

There is a lot of information out there and I'm still confused. I'm hoping this is an easy answer for someone. Yes I know raid is not a back up - before someone says it.

I've messing around with the raid reliability calculator.
https://www.servethehome.com/raid-calculator/raid-reliability-calculator-simple-mttdl-model/

I've found information like this.
Start a single-parity RAIDZ (raidz) configuration at 3 disks (2+1)
Start a double-parity RAIDZ (raidz2) configuration at 6 disks (4+2)
Start a triple-parity RAIDZ (raidz3) configuration at 9 disks (6+3)
The recommended number of disks per group is between 3 and 9. If you have more disks, use multiple groups.

 

[dandanio]

IMHO (tm), if you go with Z2 on 8 or 10 disks, with a regular (weekly) scrub - then Z2 is enough. I do not see a reason to go Z3 ever, unless you have some VERY IMPORTANT DATA to store. I sooner go multiple pools, like 2x8 z2s before going z3. Can you imagine resilvering such array? Just my 2c.

 

[SRussell]

I am still working through my ZFS setup... and I am newb so take that for what it is...

I went with a 9x 10TB RAIDz3 array for my backup. I keep a cold spare because I have not yet found how to spin down a hot spare. Keeping a spinning hot spare still does not make much sense to me since any drive activity becomes wear and tear on the drive.

 

[pricklypunter]

I would go up to 8 disks in raidz2, if capacity is your requirement, beyond that, another pool of 8 and so on. If performance is your end goal here and not capacity, you'll want to be mirroring instead

Also, just a point to note about ZFS in general. It is incredibly robust, even when things go wrong. There is a very good chance of data retrieval, even with a poorly disk or two, providing you don't panic when things go wrong and do something stupid that puts your data at risk

 

[DistantStar]

IMHO (tm), if you go with Z2 on 8 or 10 disks, with a regular (weekly) scrub - then Z2 is enough. I do not see a reason to go Z3 ever, unless you have some VERY IMPORTANT DATA to store. I sooner go multiple pools, like 2x8 z2s before going z3. Can you imagine resilvering such array? Just my 2c.

I agree with this. I've been running two 12 drive Z2's in a Norco 24 drive chassis for 8 years with zero issues. Always kept a cold spare or two around, and only ever replaced 1 drive at a time when it started throwing a lot of errors during a scrub.

 

[foxhunt]

I'll just go with my 10 drive z2. Thanks for all the feedback

 

[SRussell]

I agree with this. I've been running two 12 drive Z2's in a Norco 24 drive chassis for 8 years with zero issues. Always kept a cold spare or two around, and only ever replaced 1 drive at a time when it started throwing a lot of errors during a scrub.

What brand drives are you using?

 

[DistantStar]

What brand drives are you using?

The Hitachi 5K3000's from 2010-2014

 

[dandanio]

I am on 8TB WD Reds, shucked. 8x8TB with 2 VCS (Very Cold Spares - shelved) on a X10SDV-4C-TLN4F with 64GB of ECC DDR4 in a DS380B.

 

[T_Minus]

I think it depends on usage, at-least for me.

For instance my "home" storage is RZ2, but the backup of that is 3 drives in triple-mirror.
If I had to backup more data I would use RZ3.

Same is true for work, performance is mirrored vdev, resilient storage is rz2.