This is a good one ;-). I have worked through this issue w/ both Apple and LaCie support but no fix.
- Dell U2713HM (Rev. A00) running at 2560x1440 60hz
- Retina 15" MacBook Pro / Dual Graphics (2014 model) 16GB
- OS X 10.9.5
- LaCie 2Big Thunderbolt 2 6TB Raid Array
rMBP has two Thunderbolt 2 ports, the Dell monitor is connected to one of the two ports using a VESA compliant DP1.2 "mini display port to display port" cable (no conversion adapter).
The LaCie raid enclosure is connected to the other rMBP Thunderbolt 2 port using the supplied LaCie Thunderbolt cable
PROBLEM and WORK AROUND:
LaCie Thunderbolt 2 attached raid array will not sleep when the computer sleeps. It constantly spins the drives up and down every 20 - 30 seconds.
After much troubleshooting it was determined that by completely disconnecting the Dell monitor everything works as expected with the externally attached LaCie raid array. Simply turning the monitor off does not correct the problem. I either have to disconnect power from the monitor or unplug the mini display port cable from the rMBP Thunderbolt 2 port.
The U2713HM is set for MAC via the OSD menu and I've tried disabling DDC/CI and Energy Smart to no avail. For some reason the Dell when connected in the Thunderbolt chain is keeping the other attached peripheral actives even if the monitor front panel on/off switch is used. I have also tried to attach the monitor to the end of the TB chain by connecting it directly to the 2nd TB port on the raid enclosure... no difference in symptoms. Have also tried a different display port cable with connector adapter.. no difference. Lastly, I actually have two U2713HM monitors both rev. A00. They both act identical and exhibit the same behavior.
Just putting it out there hoping I'm not the only person on the planet to run this type of setup and that perhaps someone has a better work around versus having to physically unplug cables. Maybe someone from Dell can do an internal KB search?? Functionally everything works, monitor is an awesome display for my photography work and the LaCie array works fine. However the constant drive spin ups when it sleeps cannot be good for hardware longevity, not to mention it is annoying as can be when your working beside it on another machine.
Thanks in advance for your responses.
Unknown on our end because we do not test on apple products. Some apple users have mentioned on their forum that using a thunderbolt to DP adapter has had some success with issues of our monitors on apple hardware.