[ceph-users] Load on drives of different sizes in ceph

Hi cephers, I'm looking for some advice on what to do about drives of different sizes in the same cluster. We have so far kept the drive sizes consistent on our main ceph cluster (using 8TB drives).  We're getting some new hardware with larger, 12TB drives next, and I'm pondering on how best to configure them.  If I just simply add them, they will have 1.5x the data (which is less of a problem), but will also get 1.5x the iops - so I presume it will slow the whole cluster down as a result (these drives will be busy, and the rest will not be as much).  I'm wondering how people generally handle this. I'm more concerned about these larger drives being busier than the rest - so I'd like to be able to put for example 1/3 drive of less accessed data on them in addition to the usual data - to use the extra capacity but not increase the load on them.  Is there an easy way to accomplish this?  One possibility is to run two OSDs on the drive (in two crush hierarchies), which isn't ideal.  Can I just run one OSD somehow and put it into two crush roots, or something similar? Andras