Growing a ZFS mirror by creating a RAID-10

[l3eastie]

Granted, you can add a stripe to an existing mirror by adding a second pair of mirrored drives to a zpool, thus growing the zpool.

But if I were to wait until the first mirror was almost full before doing this, would I benefit from the performance advantages of RAID-10 i.e. does ZFS redistribute and stripe the existing data or will this only apply to new writes?

 

[jgreco]

ZFS will not _re_distribute your data. However, it will intelligently balance further I/O to the devices. It will naturally prefer the emptier vdev, though.

 

[aplats]

Signed up to ask this question, but found it with a search first! I was curious about this as well. Due to limited funds, I have only purchase 2 hard drives to start with a single mirror. It's plenty of space for me now, but down the road I might add a striped mirror--it would have been nice to have it redistribute the data to get the performance benefit. I plan on buying a 4TB external for backup, so I suppose when I need more space, I can destroy the pool and recreate it with the extra disk and then restore the data.

 

[ZFS Noob]

I plan on buying a 4TB external for backup, so I suppose when I need more space, I can destroy the pool and recreate it with the extra disk and then restore the data.

Or run a full backup to that 4TB drive, then use another 4TB drive. Move all the pool data to the second external drive so that the pool is empty, then move it back. If that external drive should fail, you had a full backup.

(But then, I'm paranoid about data...)

 

[aplats]

Or run a full backup to that 4TB drive, then use another 4TB drive. Move all the pool data to the second external drive so that the pool is empty, then move it back. If that external drive should fail, you had a full backup.

(But then, I'm paranoid about data...)

Now that's just crazy!

Just kidding, that's a good idea. Even working in our datacenter with an EMC SAN, you can't play around with not backing up...