The attempt to create a VDI Failed

When updating to Xenserver 7.1 from 6.5 we noticed this when creating a new virtual disk on our ISCSI SR. All servers are updated to the latest hotfixes and all servers are running  Error log: 2017-04-10 15:12:26,537 WARN Audit [22] - Operation failure: VMStartAction: XEN POOL 01: VM 900cf2b2-2f91-9c64-7890-f4bf88a266cb (Citrix License Server): Pool 48e15d13-b0d8-10dd-caa8-95b125361c93 (XEN POOL 01): Starting VM 2017-04-10 15:12:48,758 INFO XenAPI.Session [45] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:48,804 INFO XenAPI.Session [45] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:48,867 INFO XenAPI.Session [45] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:48,929 INFO XenAPI.Session [45] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:54,452 INFO XenAPI.Session [22] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:54,514 INFO XenAPI.Session [22] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:54,576 INFO XenAPI.Session [22] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:54,623 INFO XenAPI.Session [22] - Invoking XML-RPC method VM.assert_can_boot_here 2017-04-10 15:12:55,762 INFO Audit [Main program thread] - Operation started: VMStartOnAction: XEN POOL 01: VM 900cf2b2-2f91-9c64-7890-f4bf88a266cb (Citrix License Server): Pool 48e15d13-b0d8-10dd-caa8-95b125361c93 (XEN POOL 01): Host e9b14cc8-6408-4d93-99a8-1d5ae76552bf (XEN-02): Preparing... 2017-04-10 15:12:55,762 INFO XenAPI.Session [45] - Invoking XML-RPC method Async.VM.start_on 2017-04-10 15:12:55,793 INFO XenAPI.Session [45] - Invoking XML-RPC method task.remove_from_other_config 2017-04-10 15:12:55,840 INFO XenAPI.Session [45] - Invoking XML-RPC method task.add_to_other_config 2017-04-10 15:12:55,887 INFO XenAPI.Session [45] - Invoking XML-RPC method task.remove_from_other_config 2017-04-10 15:12:55,918 INFO XenAPI.Session [45] - Invoking XML-RPC method task.add_to_other_config 2017-04-10 15:12:55,965 INFO XenAPI.Session [45] - Invoking XML-RPC method task.remove_from_other_config 2017-04-10 15:12:55,996 INFO XenAPI.Session [45] - Invoking XML-RPC method task.add_to_other_config 2017-04-10 15:13:18,139 INFO XenAPI.Session [45] - Invoking XML-RPC method task.destroy 2017-04-10 15:13:18,186 INFO Audit [45] - Operation success: VMStartOnAction: XEN POOL 01: VM 900cf2b2-2f91-9c64-7890-f4bf88a266cb (Citrix License Server): Pool 48e15d13-b0d8-10dd-caa8-95b125361c93 (XEN POOL 01): Host e9b14cc8-6408-4d93-99a8-1d5ae76552bf (XEN-02): Started 2017-04-10 15:19:52,474 INFO Audit [Main program thread] - Operation started: CreateDiskAction: XEN POOL 01: Pool 48e15d13-b0d8-10dd-caa8-95b125361c93 (XEN POOL 01): Creating virtual disk... 2017-04-10 15:19:52,490 INFO XenAPI.Session [25] - Invoking XML-RPC method VDI.create 2017-04-10 15:20:39,885 ERROR XenAdmin.Actions.AsyncAction [25] - The attempt to create a VDI failed 2017-04-10 15:20:39,885 ERROR XenAdmin.Actions.AsyncAction [25] - at XenAPI.Response`1.parse() at XenAPI.VDI.SaveChanges(Session session, String opaqueRef, VDI server) at XenAPI.XenObject`1.SaveChanges(Session session, IXenObject beforeObject) at XenAdmin.Actions.SaveChangesAction.Run() at XenAdmin.Actions.CreateDiskAction.Run() at XenAdmin.Actions.AsyncAction.RunWorkerThread(Object o) 2017-04-10 15:20:39,885 WARN Audit [25] - Operation failure: CreateDiskAction: XEN POOL 01: Pool 48e15d13-b0d8-10dd-caa8-95b125361c93 (XEN POOL 01): Creating virtual disk...   Regards Chris