Seagate External Drive will NOT erase and is now invisible in Finder

Running 10.11.6 on an iMac and am trying to format a 2Tb Seagate Expansion Drive to use to instal a back up operating system. Have done this many times before. However this time I connected the brand new drive, opened Disk Utilities and went through the process of erasing to an Apple format and the operation failed due to

"MediaKit reports not enough space on device for requested operation. Operation failed..."

The disk is now invisible to my desktop despite disconnecting and reconnecting the disk and also restarting the iMac. I have run DiskTools which is unable to see it and DiskWarrior which can see the disk but sees it as two partitions and unusable. I have tried mounting it through DiskWarrior but failed.

The disk was brand new and arrived today from Amazon.

I really need to start a back up tonight and was wondering if there was a simple way around this problem

Many thanks

Posted on Jun 24, 2017 4:40 PM

Top-ranking reply

scottyincali

Level 1

20 points

Posted on Apr 1, 2018 6:12 PM

I used the following to format my 8TB Seagate drive. My drive, although it mounted at first, when I tried to erase it using Disk Utility, it failed and then no longer would mount at all. I opened Terminal and issued the "diskutil list" command and saw (also noted from research online) that it had a Microsoft Reserved partition which is what causes it to fail to erase using Disk Utility:

/dev/disk3 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *8.0 TB disk3

1: Microsoft Reserved 134.2 MB disk3s1

2: Apple_HFS 8.0 TB disk3s2

I issued the following command and it erased and mounted and was erasable in Disk Utility:

diskutil partitionDisk /dev/disk3 1 GPT HFS+ newdisk R

-Scott

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18 replies

kahjot

Level 4

2,463 points

Jun 26, 2017 8:08 AM in response to Geggsy125

Safer to go to directly to Partition. You can effectively erase by resetting your volume to one partition.

Aroundsp

Level 1

4 points

Jul 4, 2017 7:43 AM in response to Geggsy125

Hi!
I'm having the same problem and now my mac doesn't see the drive anymore, is "half dead" as yours.. how did you made it visible again?

Aroundsp

Level 1

4 points

Jul 5, 2017 8:37 AM in response to Geggsy125

Thank you so much for your attention!
I was trying to help a friend, but he decided to take the drive and change it for a drive to mac. He didn't notice that when he bought it..

Best regards!

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Seagate External Drive will NOT erase and is now invisible in Finder