EHD not opening

[RideForever]

Operating an iMac, running macOS High Sierra, v10.13.3 as well as a MacBookPro (MBP) bought last October, also up-to-date. I use two 8TB Western Digital MY BOOK EHDs for backing up the iMac - one (PRIMARY) only using Time Machine, the other (SECONDARY) by means of manual copy and stored offsite or taken when travelling and used with the MBP. Have just returned from lengthy absence and plugged in the SECONDARY to the iMac both indirectly through a Kensington USB3.0 7-port hub and directly to the iMac. In neither case am I getting an icon on the monitor or an indication in Finder that the EHD is being (has been) read. However, power is connected, hub is powered up, the external is chugging away and if it is disconnected in either option, there is a popup advising "Disk not Ejected Properly/Eject "Secondary BU" before disconnecting or turning it off". Reconnecting instead to the MBP, the EHD opens immediately and is seen in Finder and the icon on the screen. SUGGESTIONS WOULD BE MOST WELCOME to remedy.
David

 

[DaveWT]

The first place to check is Finder > Preferences...



Make sure there is a checkmark next to "External disks"



If that is missing on the iMac but not on the MBP, that could explain the difference.

 

[RideForever]

Thank you Dave for the directions and suggestions. All the appropriate preferences indeed were checked. After a number of hours of being connected to the iMac, the SECONDARY BU icon finally showed up on the monitor and was indicated also on the Finder under Devices. Ironically, I subsequently reconnected SECONDARY BU to the MBPro and it , this time, took almost an hour to read. This is despite both the iMac and MBPro having the same level of operating system and identical Preferences. Given that the primary purpose for having this BU is for Lightroom and 2-3 thousand photos taken while travelling, I am not sure I understand why these delays are occurring so any further thoughts would be welcome. Regards. David

 

[chas_m]

Given that the primary purpose for having this BU is for Lightroom and 2-3 thousand photos taken while travelling, I am not sure I understand why these delays are occurring so any further thoughts would be welcome. Regards. David

A drive that is very slow to mount as you describe sounds like the drive could be failing, but this could also be due to the lengthy indexing Spotlight needs to do for a drive the first” time it is mounted. As you probably have a lot of files on the drive, this could be an alternate explanation. How old are these drives?

 

[RideForever]

Charles, all the drives are new last year. Could it be fact that the drives were not read on the iMac for 3 months be the issue as we have been away?

 

[chas_m]

That being the case, it's most likely that the slow performance was due to the need for Spotlight indexing to take place. While it is possible for hard drives to fail at any time (even right out of the box), the most likely explanation is that it was doing the indexing. Keep us posted if you continue to get slow performance out of those drives, as the Spotlight indexing should be done by now.

 

[RideForever]

I suspect the indexing was the issue as opening the drives is bad to normal.