That makes sense. Thanks guys. Interesting on the pooling of storage
Given the N54L is designed for 4 drives, I'm thinking of now going with 3*2/3TB in RAIDZ1 as don't think my needs will go beyond 4/6tb for a while. I guess down the line I could either grow it by replacing with bigger drives or build another!
The other alternative seems for 4 drives seems to be a mirror of 2*2/3tb and then add another 2*Xtb in down the line, but at the cost of less 'efficient' use of the drives by using mirror rather than Z1 etc.
For critical data (basically photos) I plan to backup to Amazon glacier to mitigate risk of catastrophic failure, so don't need higher levels of redundancy which seems to be what RAIDZ2 seems to give you.
Anything i'm missing?
Given the N54L is designed for 4 drives, I'm thinking of now going with 3*2/3TB in RAIDZ1 as don't think my needs will go beyond 4/6tb for a while. I guess down the line I could either grow it by replacing with bigger drives or build another!
The other alternative seems for 4 drives seems to be a mirror of 2*2/3tb and then add another 2*Xtb in down the line, but at the cost of less 'efficient' use of the drives by using mirror rather than Z1 etc.
For critical data (basically photos) I plan to backup to Amazon glacier to mitigate risk of catastrophic failure, so don't need higher levels of redundancy which seems to be what RAIDZ2 seems to give you.
Anything i'm missing?

I seem to recall reading that the next version of EXSi increases that limit, haven't looked into it though. Do you happen to know if re-building an array on a ZFS system is particularly harsh on the disks? (Some seem to suggest that a danger is having a disk fail and then the rebuilding process on larger disks is enough to stress a 2nd disc into failing - screwing your whole array in the process
)