OS 10.9.3 Seagate External Drive Won't Mount Updated to Mavericks and now my external 1TB Seagate drive won't mount. Its icon ("Blorp") is greyed out in Disk Utility and all it says about the volume is that it is a "locked logical volume." This is not being used as a Time Machine backup drive, just an external drive. It won't even prompt for a password when I try to mount it. And it shouldn't be locked, since I turned off the encryption prior to upgrading the OS. This started when I opened up the computer and it said the drive was not ejected properly, even though it had been plugged in continuously. Can I get this drive back without reformatting it?



There is no fsck_hfs or similar process shown in Activity Monitor. I have run disk repair multiple times, and it always comes up ok:
I don't know exactly what build changed the mount behavior of OS X, but there are times when you will connect the disk and the OS will no longer mount it until the system has finished the file system check (fsck). There is no visual notification that an extended check is being made, so you have to rely on Disk Utility or the Activity Monitor and actively look to see if a check is in progress.

Connect your missing drive again and then, open activity monitor and select the CPU tab if needed. Then search for fsck - if you see a process with that name (or similar fsck_hfs, etc...) then the system has decided to check the contents before it knows to let you have read-only access to the drive or read-write access.

If that's not the case, then you may have some odd corruption that requires a repair of the drive structure (in your case select the main "Blorp" and not the indented "Blorp" in the left pane of the Disk Utility window. The dimming of the repair button is indicative of a process already running to check/repair that volume.

Most cases, this is a check that could take some time, but often is done within 5 minutes or less and not something that happens every mount but after another problem was detected or logged to that drive such as an unclean ejection or force eject.