[ceph-users] iSCSI write performance

I'm in the process of testing the iscsi target feature of ceph. The cluster is running ceph 14.2.4 and ceph-iscsi 3.3. It consists of 5 hosts with 12 SSD OSDs per host. Some basic testing moving VMs to a ceph backed datastore is only showing 60MB/s transfers. However moving these back off the datastore is fast at 200-300MB/s. What should I be looking at to track down the write performance issue? In comparison with the Nimble Storage arrays I can see 200-300MB/s in both directions. Thanks, Ryan