Synology

I did some basic setup on a Synology DS920+ for a friend of mine.  The NAS had the DSM 7.0.1 operating system on it.  The drives that were used were a pair of Toshiba 12tb, model MG07ACA12TE9, 10.9tb usable. Also a pair of Toshiba 14tb, MG08ACA14TE drives, 12.7tb usable.  Neither of these drives are on the compatibility list, but they work anyways.  

During the setup, all four drives where installed into the system and we could not create ANY volumes.  After some trouble shooting we powered down the system, installed a single 12tb drive, created a single drive pool and a single storage pool with success.  Powered down the system added a 2nd drive and added it to the existing pools.  This worked however the Synology RAID levels it took 48 hours to recalculate the RAID.  Mind you this was a completely blank set of drives! 

I then added the remaining 14tb drives.  I could not add them to the existing pools that contained the matching pair of 12tb drives.  I was able to add the two 14tb drives as a second storage and volume pools.

Then I blew away both sets of pools then created a new volume containing all four drives using the Synology default RAID(SMR) level (because it allowed for drives of different sizes and the loss of a single drive).  The amount of usable space of 35tb, unfortunately it it gave an estimate of 24 hours to optimize the pools.