RAID Query for different sized disks

[Craig_]

I've tried researching this but am not having much luck with my specific query.

Can you use different size disks in a RAID1 array, but pick an element of the larger drive not to be mirrored.

In an example, 1 4tb and 1 6tb drive
Could the 4tb drive be mirrored on the 6tb, but have the remaining 2tb on the larger drive available as a separate partitions and un-mirrored?
eg. partition the larger drive was partitioned into two 2 partition, a 4tb and a 2tb section.

If it helps, I am currently considering the QNAP TS-251 NAS.
I was hoping a successor to this (or the Synology DS215Play) would have been released by now, but I've seen no sign, but now the price on the QNAP has dropped significantly that I'm considering not waiting any longer.

 

[kanewolf]

You can mix disks in a RAID1. The mirrored portion will be the smaller of the two sizes. You can then allocate the remaining space to a second volume.

 

[Craig_]

You can mix disks in a RAID1. The mirrored portion will be the smaller of the two sizes. You can then allocate the remaining space to a second volume.

Thanks.
Would you know if this is easy to set-up with the QNP software?