EXTERNAL DRIVE NOT RECOGNISED

Discussion in 'MacBook Pro' started by brendanxx, May 8, 2016.

  1. brendanxx macrumors newbie

    Joined:
    May 5, 2015
    #1
    I have a Macbook pro late 2011 running El Capitan. My 1T samsung external drive has suddenly stopped being recognised. It is not in Finder or in disc utility. It is however in Apple About, system report, USB. Its light goes on when connected and I've connect it with the macbook on power cord. My other samsung and seagate external drives work. The non recognised 1T drive is not recognised on my wife's macbook pro. Is there someway to get it recognised? If the drive has somehow become corrupted is there a way to reformat it it if it's not being recognised? Is there some way to get the information on it without going the expensive professional data recovery route (which I can no way afford).
    Many thank in advance
    Brendan
     
  2. rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #2
    if you cant erase the hard disk with disk utility, then its most likely dead. i had a 500 gb WD that stopped mounting. it would just spin up but never mount, i just mailed it in to have it destroyed. it was just a backup

    in these situations, you need to go to the hard disk manufactures website, and see if there is a utility you can run ( like drive wizard ) to check the hard disk. they might have utilities to erase the drive

    the problem with external USB drives is they block S.m.a.r.t. which diagnoses and repairs errors automatically on the drive itself, without the need of software. someone on this forum told me they are drivers you can install to read the smart table. otherwise you have to remove the hard disk from its external enclosure and connect it directly to a computer's SATA port to check the smart system

    another problem with usb drives is that its limited to 5v @ 500 ma, and the power requirements to actually drive a hard disk might not have enough current. this is especially true of seagate hybrid drives. if the usb current is low , then the drive just beeps and never spins up.

    if there is a seperate power connector the plugs into the hard disk, see if you can replace it or test it
     
  3. MRxROBOT, May 8, 2016
    Last edited: May 8, 2016

    MRxROBOT macrumors 6502

    MRxROBOT

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    Apr 14, 2016
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    1011100110
    #3
    Is your drive the T1 Samsung external SSD or is it simply a 1TB Samsung drive in an external enclosure. If it's the latter you can try putting the drive into a new enclosure and eliminating one point of failure.
     
  4. JTToft macrumors 68040

    Joined:
    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #4
    Doesn't sound good. Does it spin up when you connect it?
    With the drive connected, run the below command and post the output inside [ CODE] [ /CODE] brackets (without the spaces)

    Code:
    diskutil list
     
  5. brendanxx thread starter macrumors newbie

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    May 5, 2015
    #5
    --- Post Merged, May 8, 2016 ---
    I'm sorry - very much a newbie - can you tell me how I run the code?
     
  6. JTToft macrumors 68040

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    Apr 27, 2010
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    Aarhus, Denmark
    #6
    - Apologies. I was not specific enough. Open Terminal, which is located in Applications -> Utilities, copy and paste the command into the window, and hit Enter. Post the output.

    Also, does the drive spin up at all? Can you hear it when you connect it?
     
  7. wwe2008 macrumors 6502

    Joined:
    Mar 10, 2008
    #7
    I had an issue with one of my external hard drives and USB3. Changed to a USB2 cord (I think its mini that fits) and that worked! Possibly due to drivers etc
     
  8. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #8
    Hi,
    terminal info:
    Last login: Sun May 8 15:30:36 on ttys000
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil list
    /dev/disk0 (internal, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *500.1 GB disk0
    1: EFI EFI 209.7 MB disk0s1
    2: Apple_HFS Macintosh HD 499.2 GB disk0s2
    3: Apple_Boot Recovery HD 650.0 MB disk0s3
    /dev/disk1 (external, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *1.0 TB disk1
    1: EFI EFI 209.7 MB disk1s1
    2: Apple_HFS SAMSUNG 999.9 GB disk1s2
    BRENDANs-MacBook-Pro:~ brendansomers$

    Yes, it makes a whirring sound when connected!
    cheers
    Brendan
    --- Post Merged, May 8, 2016 ---
    Hi,
    terminal info:
    Last login: Sun May 8 15:30:36 on ttys000
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil list
    /dev/disk0 (internal, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *500.1 GB disk0
    1: EFI EFI 209.7 MB disk0s1
    2: Apple_HFS Macintosh HD 499.2 GB disk0s2
    3: Apple_Boot Recovery HD 650.0 MB disk0s3
    /dev/disk1 (external, physical):
    #: TYPE NAME SIZE IDENTIFIER
    0: GUID_partition_scheme *1.0 TB disk1
    1: EFI EFI 209.7 MB disk1s1
    2: Apple_HFS SAMSUNG 999.9 GB disk1s2
    BRENDANs-MacBook-Pro:~ brendansomers$

    Yes, it makes a whirring sound when connected!
    cheers
    Brendan
     
  9. Fishrrman macrumors G4

    Joined:
    Feb 20, 2009
    #9
    Some thoughts:

    Have you tried a different connecting cable?

    Did the drive come with an external power supply?
    If so, have you tried using it?

    Have you tried -different- USB ports on the Macs in question?
     
  10. JTToft macrumors 68040

    Joined:
    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #10
    - Thanks. The above bit means the disk is recognised. Try simply running this and see:

    Code:
    diskutil mount disk1s2
     
  11. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #11
    Yes, I've tried another connecting cable.
    No, it doesn't have an external power supply, it runs off the mac.
    Yes, I have tried the other USB port.

    When plugged in the device's little blue light flashes as if it's properly connected.
    Problem started when I inadvertently unplugged the device manually instead of doing it through the mac.
    --- Post Merged, May 8, 2016 ---
    Got this message

    Volume on (null) failed to mount
    If the volume is damaged, try the "readOnly" option
    BRENDANs-MacBook-Pro:~ brendansomers$
    BRENDANs-MacBook-Pro:~ brendansomers$

    - how do you do a "read only" command?

    I don't understand why the device's little blue light is flashing as though it's communicating with the mac! Very strange!

    Many thanks anyway for your trouble - any further thoughts most welcome.

    Brendan
    --- Post Merged, May 8, 2016 ---
    Also, when I open disc utility I just get the spinning wheel and "loading discs" - but nothing loads and the wheel keeps spinning!
     
  12. JTToft macrumors 68040

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    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #12
    Should be:
    Code:
    diskutil mount readOnly disk1s2
    If that doesn't yield anything, run a verify disk and post the output:
    Code:
    diskutil verifyDisk /dev/disk1
     
  13. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #13
    Last login: Sun May 8 16:03:28 on ttys000
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil mount readOnly disk1s2
    Volume on disk1s2 timed out waiting to mount
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil mount readOnly disk1s2
    Volume on disk1s2 timed out waiting to mount
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil verifyDisk /dev/disk1
    Started partition map verification on disk1
    Checking prerequisites
    Checking the partition list
    Checking the partition map size
    Checking for an EFI system partition
    Checking the EFI system partition's size
    Checking the EFI system partition's file system
    Checking the EFI system partition's folder content
    Checking all HFS data partition loader spaces
    Checking booter partitions
    Checking Core Storage Physical Volume partitions
    The partition map appears to be OK
    Finished partition map verification on disk1
    BRENDANs-MacBook-Pro:~ brendansomers$
     
  14. JTToft macrumors 68040

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    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #14
    - Disappointing.

    Run
    Code:
    diskutil verifyVolume disk1s2
    And then
    Code:
    diskutil repairVolume disk1s2
    Have you tried the drive on another computer just to see?
     
  15. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #15

    Yes, I tried it on another macbook pro - didn't work.

    Her's the terminal stuff

    Last login: Sun May 8 17:09:33 on ttys000
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil verifyVolume disk1s2
    Started file system verification on disk1s2 SAMSUNG
    Verifying file system
    File system check exit code is 8
    Error: -69845: File system verify or repair failed
    Underlying error: 8: POSIX reports: Exec format error
    BRENDANs-MacBook-Pro:~ brendansomers$ diskutil repairVolume disk1s2
    Started file system repair on disk1s2 SAMSUNG
    Repairing file system
    File system check exit code is 8
    Updating boot support partitions for the volume as required
    Error: -69845: File system verify or repair failed
    Underlying error: 8: POSIX reports: Exec format error
    BRENDANs-MacBook-Pro:~ brendansomers$

    I guess it's not looking too good!
    Is there any way to reformat the disc if the macbook doesn't recognise it?
     
  16. JTToft macrumors 68040

    Joined:
    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #16
    - It does indeed not look good. I understood you would like to pull data from it, which is why I haven't yet recommended a reformat. However, the procedure for that - which will completely erase its data - is:

    Code:
    diskutil eraseDisk JHFS+ NAME disk1
    Replacing NAME with the name you would like the disk to have.
     
  17. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #17
    Many thanks - yes, of course I would have wanted to pull data from it but alas that seems not to be. So, rather than waste the drive I guess I'll have to reformat it - hopefully that will work! I will let you know.
    cheers
    Brendan
    --- Post Merged, May 8, 2016 ---
    Just to make sure - the external drive is disk1 - I wouldn't want to erase my macs hard drive!
    --- Post Merged, May 8, 2016 ---
    Will it a
    Does it actually format the disc as well as erasing? I guess I need it to be NFTS formatted
     
  18. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #18
    No you don't want NTFS that is a Windows format, and is read only from OS X you'd only be able to read the volume. You want to us the Mac OS X journaled format for full compatability or ex fat if you want to use on Windows machines as well.
     
  19. JTToft macrumors 68040

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    Apr 27, 2010
    Location:
    Aarhus, Denmark
    #19
    - Yes, disk1 is the external. If you look at the very first output you posted, the internal with Macintosh HD on it is disk0.
    Also, it's impossible to erase the internal drive when you're booted from it. So if you entered "disk0" by mistake, it would just give an error and abort.

    - Format = Erase, in Apple speak. My command formats it as OS X Extended (Journaled) which is the standard Mac file system and what you have now. NTFS is for Windows and is read only on OS X. If you do want that, replace "JHFS+" in my command with "NTFS".
     
  20. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #20
    Much obliged everyone - very kind to a computer ignoramus - I shall back everything up on another disk and erase/format the samsung tomorrow.
    Many thanks for your time!
    Brendan
     
  21. duervo macrumors 68000

    duervo

    Joined:
    Feb 5, 2011
    #21
  22. brendanxx thread starter macrumors newbie

    Joined:
    May 5, 2015
    #22
    Well! Last night I decided to just go ahead and erase/format the disc - just before I did I noticed that the disc was back in Finder! Incredible! Perhaps/probably it was the repair command through Terminal that although it did not work, worked enough to tweak the problem and solve it!
    So, many thanks to you all for your help and interest!
    All the best
    Brendan
    --- Post Merged, May 9, 2016 ---
    Now the disc is shoring in disc utility should I run first aid on it?
    --- Post Merged, May 9, 2016 ---
    Now the disc is showing in disc utility should I run first aid on it?
     

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