RAIDZ1 vs RAIDZ2

[qwerion]

I'm considering putting together a NAS with the following parts.

Pentium G3220 (ARK states it has ECC support)
ASRock E3C224
8GB ECC
2x Old Seagate 1.5TB (by old, I mean 2008-vintage)
2x New Cheapest 2TB drives I can get (basically the same price as 1.5TB drives these days)

I had previously been running the old HDDs in a manual mirror in my main computer, but spun down most of the time. My main concern is covering for their age.

As such, would a RAIDZ1 with a hot spare or a RAIDZ2 be better in this regard? I think the main argument against the Z1 hot spare is worries of a correlated failure of the two older drives during a resliver, and typing this out leans me towards the Z2.

 

[Dusan]

Go with RAIDZ2. There is no benefit to RAIDZ1 + spare, as spares to do autoreplace in FreeNAS. With RAIDZ2 your "spare" is always silvered in. If a drive fails you do not need to wait for the resilver to finish to get to 1 drive redundancy.

 

[joeschmuck]

Keep in mind that when you create your RAIDZ2 (or any RAIDZ for that fact) will only count your hard drive space by the smallest drive in the pool so all your drives will be treated as 1.5TB drives, even the 2TB drives. When you replace the 1.5TB drives with 2TB drives then your pool will automatically expand to use up all the extra space. Just info so you don't think you got screwed when you figure out you don't have exactly as much as you might have hoped for.