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This advice isn't actually totally correct. If you build a volume, you can add more zdevs to it. My suggestion is to avoid RAIDZx and go with mirrors. To add

This advice isn't actually totally correct. If you build a volume, you can add more zdevs to it. My suggestion is to avoid RAIDZx and go with mirrors. To add more storage, just add another pair of drives and add it to your pool. Here is what my main `tank` looks like: pool: tank state: ONLINE scan: scrub repaired 0B in 4h59m with 0 errors on Tue Jul 4 12:47:02 2017 config: NAME STATE READ WRITE CKSUM tank ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 wwn-0x50014ee20eba1695 ONLINE 0 0 0 wwn-0x50014ee20eba337e ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 wwn-0x50014ee2640efb3a ONLINE 0 0 0 wwn-0x50014ee2b964ef3f ONLINE 0 0 0 mirror-2 ONLINE 0 0 0 wwn-0x50014ee2b964f2d5 ONLINE 0 0 0 wwn-0x50014ee2b964f4f4 ONLINE 0 0 0 cache wwn-0x5002538d704e9ff1-part4 ONLINE 0 0 0 errors: No known data errors You can simply add another mirrored pair and get more storage. Or, you can update an existing mirror by adding new drives, then removing the old ones. Mirroring has better performance and IOPs than striped raid too. If you feel that mirrors might be less reliable than RAIDZx, I'd suggest you read up about it - generally mirrors are more reliable (and you could mirror 3 drives if you liked, get more throughput and IOPs - or have a hot spare).

gaadd33 9y ago
As you add mirrored pairs your data isn't evenly distributed across all stripes is it?
- ioquatix 9y ago
  The simple answer to your question is no. The more complex answer is that over time as you write more data, ZFS will re-balance the distribution of data over the available zdevs.
  - takeda 9y ago
    I think the concern is that if you have two disks die it is not a big deal, unless those two disk happen to be of the same pair[1], then most likely all data is lost. [1] if you're not careful, this is actually very likely to happen. If you purchase 2 disks at the same time, and they are under the same usage patterns (which they will be when working in a pair), under the same temperature then they are very likely to die at the same time.

gaadd33 9y ago

As you add mirrored pairs your data isn't evenly distributed across all stripes is it?

ioquatix 9y ago
The simple answer to your question is no. The more complex answer is that over time as you write more data, ZFS will re-balance the distribution of data over the available zdevs.
- takeda 9y ago
  I think the concern is that if you have two disks die it is not a big deal, unless those two disk happen to be of the same pair[1], then most likely all data is lost. [1] if you're not careful, this is actually very likely to happen. If you purchase 2 disks at the same time, and they are under the same usage patterns (which they will be when working in a pair), under the same temperature then they are very likely to die at the same time.