On 31th of July this year we were contacted by DELL informing us of urgent firmware updates regarding some SSDs and some Raid-Controllers. But i guess the main thing was on the SSDs because of some "hang"-cases. So - please use the latest Nautilus and update the drives. Attention: You HAVE TO use Nautilus (in UEFI mode - if you have installed ESXi6 via BIOS, make sure to swith to UEFI before booting Nautilus but make sure even more to switch back to BIOS when using ESXi again IF you installed ESXi via BIOS). For the drive FW you can´t use LC at this time, even with the R730 series. So always have the latest Nautilus on hand after doing the usual SUU stuff.
http://www.dell.com/support/home/us/en/04/Drivers/DriversDetails?driverId=TTRG8
Best,
Joerg