How can i fix an external hard disk that "is no longer readable by this computer"?

I been having this problem with 2 of my disks ...and other people have it to with no real solution to it. Anyone out there figured this out? This happened after i added the hard disk on another computer (PC)

Please help!

Why not reboot them using disk utilities? "Mac OS Extended (Journaled)" would be the correct format...

bossen means to say "reformat" them.

It's hard to say what has happened to those disks, but you imply that they were connected to your Mac and then you moved the to the PC and then moved them back to the Mac. Were they originally formatted for the Mac? If so, I would imagine that connecting them to the PC overwrote (or at least damaged) the directory, which would explain the issue you're having.

Just out of interest, isn't reboot and reformat the same thing? I thought so...

Hello and thanks for your answer...

i tried rebooting to Mac OS Extended (Journaled)

i get the posix error... i get his error with any format!

The disks were formatted for mac and they were working fine...but when they were connected on PC, (on 2 different PC's at different times), this happened...

I even tried formatting one of the disks (8 bg lacie usb) on a windows 8 PC but it just took forever and it never really finished the procedure.

I even tried formatting through the terminal on the mac and still get the same posix error!

bossen said:

Just out of interest, isn't reboot and reformat the same thing? I thought so...

Click to expand...

They are not.

Generally, "reboot" means to restart your operating system.


for the op:
Have you tried connecting them with a different cable?

No i havent...one of them is a small lacie USB it doenst have a cable,...but the other one does...would that make a difference? I am not sure if it accepts a firewire though

Have seen numerous reports of a faulty cable causing a posix error - only reason for suggesting it.

Could also be that the partition map has been broken if you created &/or formatted additional partitions from Windows.
You might try this route to see if that can be repaired - link.

Hi i am will try your solution , but first check this out

i tried to reformat my 500 gb hard disk and it managed to do it..but when i tried to eject it it wouldnt work...so i tried to repair it but it didnt work

check this screenshot out

imgur: the simple image sharer

"She's dead, Jim." Unless you have a power supply failing for the external drive, or the cable is bad, the drive has headed south.