WD External Drive Automatically Unmounts I am running OS X 10.10 on a Mac Pro and I am connecting a 2TB My Book VelociRaptor Duo to it via Thunderbolt.  If I leave the drive formatted in RAID everything works just fine.  I need it formatted in JBOD, but whenever I do so, the drive mounts for about 3 seconds and automatically ejects itself.  After it ejects I can see it in Disk Utility, where I can right click and mount it again, but it still only stays mounted for about 3 seconds.  Can anyone help?  I can't even use this drive because of this.
Oh! It's same things happen to me.
I could use it by JBOD format after few weeks.
But recently It suddenly start 'UN-mount' behavior.
I use iMac5k 2014 with OS X 10.10.5 (14F27)
I tried another TB cable, but fail.