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EXTERNAL DRIVE NOT RECOGNISED

B

brendanxx

macrumors newbie
Original poster
May 5, 2015
29
4
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
 
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
 
brendanxx said:
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
Click to expand...

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.
 
Last edited:
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
 
JTToft said:
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
Click to expand...
[doublepost=1462706672][/doublepost]I'm sorry - very much a newbie - can you tell me how I run the code?
 
brendanxx said:
[doublepost=1462706672][/doublepost]I'm sorry - very much a newbie - can you tell me how I run the code?
Click to expand...
- 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?
 
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
 
brendanxx said:
[doublepost=1462706672][/doublepost]I'm sorry - very much a newbie - can you tell me how I run the code?
Click to expand...

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
[doublepost=1462718188][/doublepost]
brendanxx said:
[doublepost=1462706672][/doublepost]I'm sorry - very much a newbie - can you tell me how I run the code?
Click to expand...

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
 
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?
 
brendanxx said:
/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
Click to expand...
- Thanks. The above bit means the disk is recognised. Try simply running this and see:

Code: 
diskutil mount disk1s2
 
Fishrrman said:
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?
Click to expand...

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.
[doublepost=1462719669][/doublepost]
JTToft said:
- Thanks. The above bit means the disk is recognised. Try simply running this and see:

Code: 
diskutil mount disk1s2
Click to expand...
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
[doublepost=1462720748][/doublepost]Also, when I open disc utility I just get the spinning wheel and "loading discs" - but nothing loads and the wheel keeps spinning!
 
brendanxx said:
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?
Click to expand...

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
 
JTToft said:
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
Click to expand...

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$
 
brendanxx said:
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$
Click to expand...
- Disappointing.

Run
Code: 
diskutil verifyVolume disk1s2

And then
Code: 
diskutil repairVolume disk1s2

Have you tried the drive on another computer just to see?
 
JTToft said:
- Disappointing.

Run
Code: 
diskutil verifyVolume disk1s2

And then
Code: 
diskutil repairVolume disk1s2

Have you tried the drive on another computer just to see?
Click to expand...


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?
 
brendanxx said:
I guess it's not looking too good!
Is there any way to reformat the disc if the macbook doesn't recognise it?
Click to expand...
- 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.
 
JTToft said:
- 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.
Click to expand...

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
[doublepost=1462727845][/doublepost]Just to make sure - the external drive is disk1 - I wouldn't want to erase my macs hard drive!
[doublepost=1462728035][/doublepost]Will it a
brendanxx said:
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
[doublepost=1462727845][/doublepost]Just to make sure - the external drive is disk1 - I wouldn't want to erase my macs hard drive!
Click to expand...
Does it actually format the disc as well as erasing? I guess I need it to be NFTS formatted
 
brendanxx said:
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
[doublepost=1462727845][/doublepost]Just to make sure - the external drive is disk1 - I wouldn't want to erase my macs hard drive!
[doublepost=1462728035][/doublepost]Will it a

Does it actually format the disc as well as erasing? I guess I need it to be NFTS formatted
Click to expand...

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.
 
brendanxx said:
Just to make sure - the external drive is disk1 - I wouldn't want to erase my macs hard drive!
Click to expand...
- 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.

brendanxx said:
Does it actually format the disc as well as erasing? I guess I need it to be NFTS formatted
Click to expand...
- 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".
 
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
 
brendanxx said:
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
Click to expand...

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
[doublepost=1462780401][/doublepost]Now the disc is shoring in disc utility should I run first aid on it?
[doublepost=1462780447][/doublepost]Now the disc is showing in disc utility should I run first aid on it?
 
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