[OpenIndiana-discuss] what to setup with 4 matched disks

[James]

On 01/11/2020 18:10, Harry Putnam wrote:

> I've been coasting along for several years only using matched and
> mirrored pairs of disks.
>
> Now I would like to do some experimenting with some of the other
> possible setups.  I'm thinking maybe raidz2 or raidz3.

How much data do you have?  For small amounts stick with mirrors.

Do you own the HDDs already?  For 4TB of storage a mirror is about the 
same price as raidz because the price per capacity of HDDs goes up below 
4TB and with raidz you need more HDDs so the space efficiency of raidz 
is lost to cost.  Less capacity and mirror wins easily.
eg, 3 x 2TB in raidz1 vs 2 x 4TB in mirror
     3 x 72 = 216 GBP vs 2 x 100 = 200 GBP
eg, 4 x 2TB in raidz2 vs 3 x 4TB mirror.
     4 x 72 = 288 GBP vs 3 x 100 = 300 GBP


A simple small mirror needs less SATA ports, case slots and electricity.
Mirror is faster.
Mirror is more flexible, you can add or remove HDDs with a mirror, 
converting raidz1 to raidz2 can not be done.
With only 4 HDDs and not much data I'd use 2 x mirror zpool, you can 
expand one pool only, with raidz you have to swap all drives to expand, 
with 2 pools you can remove half your storage and move physically.


"zfs mirror vs raidz":
https://jrs-s.net/2015/02/06/zfs-you-should-use-mirror-vdevs-not-raidz/
etc.


James.