Are you using many VM’s or Docker containers? If so it might be worth keeping the 250Gb SSD as a cache drive and use the 1TB drive via the Unassigned Devices plugin for storing VM images to get maximum performance. Of course the converse is also possible, and you should select the option that best supports your work pattern.
if you go such a route then you will not have redundancy on the SSD’s but you could look at the CA Backup and VM backup plugins as a way of automatically backing their contents up to the array at intervals of your choosing.