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Comment by chromatin | Hacker News Reader

> ZFS is nearly perfect but when it comes to expanding capacity it's just as bad as RAID.

if you don't mind the overhead of a "pool of mirrors" approach [1], then it is easy to expand storage by adding pairs of disks! This is how my home NAS is configured.

[1] https://jrs-s.net/2015/02/06/zfs-you-should-use-mirror-vdevs...

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This is also exactly how mine is done. Started off with a bunch of 2TB disks. I've now got a mixture of 16TB down to 4TB, all in the original pool.

Looks good. I don't mind the overhead. That seems to be much more resilient compared to RAID5/6 and its ZFS equivalents and addresses all the concerns I outlined in this comment:

https://news.ycombinator.com/item?id=39068493

I'm still somewhat alarmed by the possibility of the surviving mirror drive failing during resilver and destroying the pool... Are there any failure chance calculators for this pool of mirrors topology? No doubt it's much lower than the RAID5/6 setups but still.

Is this topology usable in btrfs without the famous reliability issues? How good is ZFS support is on Linux? I'm a Linux guy so I'd really like to keep using Linux if possible. Maybe Linux LVM/mdadm?

50% storage efficiency is a tough pill to swallow, but drives are pretty big and the ability to expand as you go means it can be cheaper in the long run to just buy the larger, new drives coming out than pay upfront for a bunch of drives in a raidz config.

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