Thanks for the very quick response.
Yes I'm running multiple pools.
1 is for photos and music, and has duplication on it, but I don't want/need an SSD adding to this pool.
2 pools hold TV & Movies, which I do want to add an SSD to, to speed up copying of files to the pool from the network, or from other local SSDs on the server.
The 4th pool is a big pool of 8TB disks, which CrashPlan backs up the 3 other pools to.
Looks like one of tomorrow's jobs is to find space in the server, to install the SSD into, and then reconfigure DrivePool to use the new partitions.
J