External drive, Seagate, permissions changed after upgrading to OS Sierra, iMac

[bristlee1]

Hi There, I have a Seagate 5T external, it's been working great on my iMac (2013) until I upgraded to OS Sierra. Now it is read only. Reformatting is not an option as it currently holds 2.5 T of data. Any help would be appreciated. Thank you

 

[SuperSoph_WD]

Welcome to the TH Community, @bristlee1!

I'd recommend you check if your external HDD is recognized in Disk Utility on the Mac. If it is, you can easily check the drive for defects from there and also fix the permissions issue. If that doesn't help, I'd recommend finding access to another Mac OS X computer and check how the external drive would get recognized there. As soon as you can access your data, make sure you back it up to one more storage location/drive as well. Remember that 'backup' means that you have your data stored in at least two (2) locations. Moving data from your system drive to an external hard drive is not a backup, unless there is already a duplicate of the file on a different drive.

Hope this helps. Keep me posted!
SuperSoph_WD

 

[Jacquivm4]

Did you get an answer for this?
I think it has somehow reformatted to NTFS! As the same thing has happened to me!
How could it do this with the data on and how can I change it back without taking the dates off!

 

[SuperSoph_WD]

Did you get an answer for this?
I think it has somehow reformatted to NTFS! As the same thing has happened to me!
How could it do this with the data on and how can I change it back without taking the dates off!

Welcome to the TH Community, @Jacquivm4!

It would be really helpful if you share more details about your issue with your Mac OS external HDD. Have you connected the drive to a Windows OS machine recently? I'd also suggest you post some screenshots from your Disk utility and how the external appears there. It would also be a great idea to run the diagnostic test through the Disk Utility. I've shared a tutorial on how to execute this in my previous post to this thread. If the hard drive is in Read-only state, make sure you click on Repair Disk Permissions.
If you are able to access your files from another Mac OS computer, make sure you back them up! This is the surest way to avoid any potential data loss. If you say that it got reformatted to NTFS, then check how the external appears on a Windows PC/laptop.

Give it a shot and let me know how it goes.
Good luck!
SuperSoph_WD

 

[silverhammernz]

Did you get an answer for this?
I think it has somehow reformatted to NTFS! As the same thing has happened to me!
How could it do this with the data on and how can I change it back without taking the dates off!

Welcome to the TH Community, @Jacquivm4!

It would be really helpful if you share more details about your issue with your Mac OS external HDD. Have you connected the drive to a Windows OS machine recently? I'd also suggest you post some screenshots from your Disk utility and how the external appears there. It would also be a great idea to run the diagnostic test through the Disk Utility. I've shared a tutorial on how to execute this in my previous post to this thread. If the hard drive is in Read-only state, make sure you click on Repair Disk Permissions.
If you are able to access your files from another Mac OS computer, make sure you back them up! This is the surest way to avoid any potential data loss. If you say that it got reformatted to NTFS, then check how the external appears on a Windows PC/laptop.

Give it a shot and let me know how it goes.
Good luck!
SuperSoph_WD

 

[silverhammernz]

For the record this has also happened to my External Seagate 4T drive on Mac OS Sierra. Fortunately for me I have only just bought it and have no critical data on it. It formatted ok (Mac extended journaled) then I started copying files from another drive and it only got so far when it hit the "can't write to this disk because it is read only" error. I checked permissions and noticed Read & Write was set ok for admin but "everyone" was only on Read. I tried to change that setting but it just wouldn't let me, I guess because it couldn't write to the disk. So I hooked up the drive to another machine with Yosetime and it worked fine, passed the verify disk test and allowed me to copy anything to it. it also let me change permissions on "everyone". So then back to Sierra and worked for a short time then reverted back to the same old error. There is nothing wrong with the disk. It seems to be a weird thing with Sierra and maybe the fact that this disk started out life formatted ntfs. I don't know, still working on it but Sierra seems to be the culprit. I will now try formatting the disk again on my other machine.

 

[silverhammernz]

My problem got more complicated. I was finding the drive would work ok after a reboot, but after trying to transfer a big file it would go into "can't write" mode. It turned out to be my USB3 hub. Changed that and it came right.