My Book Pro 4TB USB 3 - External Drive prevents iMac to shut down correctly

WD External Drives External Drives for Mac
1

Since some years I am using the 2 TB-Version of the My Book Pro external drive (USB) with my iMac (El Capitan) as Time Mashine Backup wichout any problems. The iMac is also correctly shutting down.

Now I bought a new My Book Pro, 4TB-Version, USB 3 for replacing the old drive (I am still using the old drive for normal data storage in parallel).It is partintioned in two drives, one for the time mashine backup and the second partition as a small emergency partition.

Every time I want to shut down my iMac - independend, wether I have switched the time mashine on or off - the iMac is not shutting down correctly: The screen is switched to black, but the arrow of the mouse is not switched to the spinning symbol, which shows the ending of the shut down process. In this state (showing still the mouse arrow) the mac can stay for hours - until I switch it off using the external switch.

If I eject the USB drive manually from finder (both partitions of the 4 TB drive), the iMac is shutting down without problems. It seems, that the drive does not log out correctly when the MacOS X is starting the shut down process.

Any ideas?

Thanks

Martin

2

It may be possible for an idle process related to the RAID system to still be active in your system. Try testing after uninstalling WD Drive Utilities or changing the RAID level (This will erase the hard drive) to RAID 1 or RAID 0 as opposed to JBOD with multiple volumes.