89      iPhone_iPad_Mac_apple

Seirra Cannot detect Transcend external HDD

I cannot see my external hard drive (2 GB) neither in Finder nor in Disk Utility and not even in Terminal. I tried on every usb port.

It works fine on Windows - but not on my MacBook Pro (Sierra OS 10.12.6). Following is the result of the `diskutil list` command in terminal.

    /dev/disk0 (internal, physical):

       #:                       TYPE NAME                    SIZE       IDENTIFIER

       0:      GUID_partition_scheme                        *500.3 GB   disk0

       1:                        EFI EFI                     209.7 MB   disk0s1

       2:          Apple_CoreStorage Macintosh HD            499.4 GB   disk0s2

       3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

    /dev/disk1 (internal, virtual):

       #:                       TYPE NAME                    SIZE       IDENTIFIER

       0:                  Apple_HFS Macintosh HD           +499.1 GB   disk1

                                     Logical Volume on disk0s2

                                     DB3F5001-CD6B-40BB-A6B9-2AC9DF220FAA

                                     Unencrypted

The drive format is exFAT.

How can I fix the problem?

The weird thing is that Seirra 10.12.5 can detect it with no issues. But the Seirra 10.12.6 cannot.

What you posted is your inside startup disk only.

3 partitions: EFi (some firmware of the mac on it), Boot Recovery (the "recovery partition"), and Core Storage ( your MacOs/Startup  partition)

Obviously the external is not detected, not even with diskutil list.

If this disk is new, bring it back. Depending where you are, you have 1 yr or 2 yrs guarantee.

If the disk is old, it may be (very, very) dead; or the cable is broken.

Have you been using it already? how is/was it formatted?

Can you check if it is visible on a Windows machine?

the hard drive is 2 years old.

I can use it on windows with no issues.

Also, I tested it on my friend's macbook and it worked but when we try to connect it the second time the OS (Seirra) couldn't detect it - which is weird.

All usb ports are working. Tried another HDD on my macbook and the OS is detecting it.

Everything is fine with HDD. Nothing is broken. Fully functional.

Ok, not the worst....

The registers are damaged I suppose.

1. When you can see it on  the Windows computer

a.  make a backup of the disk to have a backup of your data.

b. then start a mac, that "sees" it, in the Recovery Partition (holding the CMD+R keys while starting up), it is slow,

after start up run DiskUtility, select the disk and click the FirstAid button, it will read and try to repair the registers and it should end with "...seems OK". If it does not end with OK, do it again, and again , and again until it ends with OK.

Then format the disk again GUID Partition Table, Mac OS Extended (journaled).

If it never ends with OK it may be visible, when you start normally. It is still not good: make a diskimage with Diskutil, so that you have again a  backup of your data.

2. when that does not work, having a backup of your data on the Windows machine,

a. connect it to the Windows machine and format the disk as Exfat, or even Fat.

b. then connect it to the mac, it should be seen, and Partition/Erase (with Disk Utility) the disk: GUID Partition Table, Mac OS Extended (journaled), or if you want GUID Partition Table, Exfat.

最后更新：2017-09-03 16:26:26

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