Ongoing problems with this combination with VSAN, but I'm finding (likely related) issues with Dell PERC H730 mini controller used to provide simple internal datastores - the controller appears to stall periodically with commands taking as much as 30 seconds to complete. Needless to say the machines are crippled performance-wise.
Some relevant entries from vmkernel.log:
2016-05-30T17:07:10.033Z cpu0:33230)ScsiDeviceIO: 2613: Cmd(0x439dc0c328c0) 0x2a, CmdSN 0x2b8b from world 32780 to dev "naa.6141877059d6b1001e6327a60b2ff1b7" failed H:0x2 D:0x0 P:0x0 Possible sense data: 0x0 0x0 0x0.
2016-05-30T17:07:10.257Z cpu5:36702)WARNING: VSCSI: 3697: handle 8201(vscsi0:0):WaitForCIF: Issuing reset; number of CIF:1
2016-05-30T17:07:10.257Z cpu5:36702)WARNING: VSCSI: 2627: handle 8201(vscsi0:0):Ignoring double reset
2016-05-30T17:07:11.309Z cpu5:32794)NMP: nmp_ThrottleLogForDevice:3231: last error status from device naa.6141877059d6b1001e6327a60b2ff1b7 repeated 2560 times
...
2016-05-30T17:07:15.526Z cpu3:36496)lsi_mr3: fusionWaitForOutstanding:2655: megasas: [ 5]sec waiting for 1 commands to complete
2016-05-30T17:07:15.529Z cpu3:36496)VSCSI: 2661: handle 8201(vscsi0:0):Completing reset (0 outstanding commands)
2016-05-30T17:07:17.169Z cpu0:32807)lsi_mr3: mfi_TaskMgmt:313: Processing taskMgmt virt reset for device: vmhba0:C2:T0:L0
2016-05-30T17:07:17.169Z cpu0:32807)lsi_mr3: mfi_TaskMgmt:317: VIRT_RESET cmd # 321473
2016-05-30T17:07:17.169Z cpu0:32807)lsi_mr3: mfi_TaskMgmt:321: ABORT
2016-05-30T17:07:17.169Z cpu0:32807)lsi_mr3: fusionWaitForOutstanding:2655: megasas: [ 0]sec waiting for 2 commands to complete
2016-05-30T17:07:20.035Z cpu4:32891)HBX: 2802: 'datastore1': HB at offset 3227648 - Waiting for timed out HB:
2016-05-30T17:07:20.035Z cpu4:32891) [HB state abcdef02 offset 3227648 gen 11 stampUS 808213540 uuid 574c7033-8f63506c-f92b-44a8424a559e jrnl <FB 309806> drv 14.61 lockImpl 3]
Plus state in doubt entries as well. We've observed this on various Rx30 machines with RAID-10 and RAID-50 configurations. Read-ahead/write-back policy.
This is with vanilla ESXi 6 update 2 (3620759), lsi-mr3 version 6.903.85.00-1OEM driver 25.4.0.0017 firmware. System BIOS and other firmware is all current. All firmware has been re-flashed.