[SOLVED] Help! WD 4TB External Hard Drive is read only for my Mac.

[chillatiger]

I love how these problems begin with, "I just bought..." which is where my question begins. I just bought a WD 4TB External Hard Drive. It was working great, reading and writing. Now it's read only. I don't have anything large enough to copy the files onto before trying any of these solutions. However, my question is why - when working perfectly one minute - it would decide not to the next? When I have flash drives that worked fine then went to read only and won't let me do a raid on them. It makes me wonder if I will be able to do a raid on the 4TB HD after a replacement comes.

 

[JustSomeJoe]

Presumably the drive is formatter for OS X (and not NTFS), have you tried running a Verify Disk, and (possibly) a Verify Permissions?

 

[SuperSoph_WD]

Welcome to the community, chillatiger!

I'm sorry to hear about your problems with your brand new WD external. @JustSomeJoe actually has a point. Can you tell me the model of the external drive though? You can check the product page of the drive on our website and see if it comes pre-formatted for Windows OS or Mac OS X.
My guess is it's formatted in NTFS and that's why it turns up as read-only on your Mac. You can easily change that by re-formatting the drive. However, keep in mind that if you have any data saved onto it, it will be erased.
If you plan to use the external only on Mac OS computers, you can simply change the file system to HFS+ and reformat the drive.
Here's a tutorial that can help you with that: http://products.wdc.com/support/kb.ashx?id=e1ZvhN
If you have Windows computers as well and would like to access (read and write to) the external from both operating systems, then you'd need to use the exFAT/FAT32 file system. Here's another tutorial that explains how to do that: http://products.wdc.com/support/kb.ashx?id=Wtbgrd
However, the latter file system has some limitations, you can check those here: http://products.wdc.com/support/kb.ashx?id=X1kN54

Hope this was helpful. Let me know if you need further assistance!
SuperSoph_WD

 

[MCristian]

Welcome to the community, chillatiger!

I'm sorry to hear about your problems with your brand new WD external. @JustSomeJoe actually has a point. Can you tell me the model of the external drive though? You can check the product page of the drive on our website and see if it comes pre-formatted for Windows OS or Mac OS X.
My guess is it's formatted in NTFS and that's why it turns up as read-only on your Mac. You can easily change that by re-formatting the drive. However, keep in mind that if you have any data saved onto it, it will be erased.
If you plan to use the external only on Mac OS computers, you can simply change the file system to HFS+ and reformat the drive.
Here's a tutorial that can help you with that: http://products.wdc.com/support/kb.ashx?id=e1ZvhN
If you have Windows computers as well and would like to access (read and write to) the external from both operating systems, then you'd need to use the exFAT/FAT32 file system. Here's another tutorial that explains how to do that: http://products.wdc.com/support/kb.ashx?id=Wtbgrd
However, the latter file system has some limitations, you can check those here: http://products.wdc.com/support/kb.ashx?id=X1kN54

Hope this was helpful. Let me know if you need further assistance!
SuperSoph_WD

The explanations on the links work fine with 1TB and 2TB WD HDDs but not with the 4TB version. All is ok till step 8 after that Disk Utility opens a message that says that the disk can't be formatted, without other explanations. I tried also with 2 partitions of 2TB. The same result, I tried both with exFAT and FAT. The same result.

A solution to the problem will be welcomed.

I'm installing now El Capitan, maybe is working with it.

 

[JustSomeJoe]

To access 4TB you need to be using GPT not MBR.

 

[MCristian]

Thank you!