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ergo · Jan 4, 2012, 07:30 PM

My external hard drive does not appear on my desktop when connected; why not and what do I do to get it to show?

MacBook Pro w/OS 10.6.8

pendragon · Jan 4, 2012, 07:54 PM

Many possibilities, but let's do the easy ones first.

In Finder/Preferences>General, do you have " External disks" enabled?

ergo · 09:55 PM

Yes,it's enabled.

My ext.HD does show in Disk Utility in the list on the left side but no where else.

reader50 · Jan 5, 2012, 04:22 AM

How is your external HD connected to your Mac?

In Disk Utility, does it show as mounted? When you select it, that info appears in the lower pane.

Mrjinglesusa · Jan 5, 2012, 01:45 PM

Hopefully it's something minor, but I had this occur recently as well. It was my Time Machine backup disk too. Stopped showing in Finder. Showed up in Disk Utility but I couldn't do anything with it (format, repair, unmount, etc.).

Disk is completely borked and not accessible to retrieve files. Basically a complete HD failure.

I hope that's not the case with yours...

ergo · Jan 5, 2012, 11:12 PM

My external HD is connected via firewire cable.
When booting up with ext. HD connected, I get the notice w/red exclamation mark telling me: "The disk you inserted was not readable by this computer".
I then have the option to initialize....I click "initialize" and am taken to Disk Utility where my ext. HD shows on the list on the left panel but "verify" and "repair" permissions as well as "verify" disk are grayed out and unusable.
I then selected "erase" (zero out data). Bare in mind that this ext.HD is empty, my main one with all backed up data is at another location and is not readily available, and I then get the notice:"Disk erase failed with the error: Posix reports:
The operation couldn't be completed. Cannot allocate memory."
Even though the disk is supposedly empty, I want a clean disk onto which I can back up what's currently on my machine's HD.
"Smart Utility" tells me that my overall Smart status PASSED but still, I wonder if my machine's HD is on the way out.
I attempted to set up "Time Capsule" (I've never used it before since I prefer to manually back up onto my ext. HD) but it tells me that it can't find an Airport device even though my Airport is functioning normally.
Anyway, I just can't use my ext.HD at this time and am totally flummoxed.

Mrjinglesusa · Jan 5, 2012, 11:18 PM

Originally Posted by ergo

My external HD is connected via firewire cable.
When booting up with ext. HD connected, I get the notice w/red exclamation mark telling me: "The disk you inserted was not readable by this computer".
I then have the option to initialize....I click "initialize" and am taken to Disk Utility where my ext. HD shows on the list on the left panel but "verify" and "repair" permissions as well as "verify" disk are grayed out and unusable.
I then selected "erase" (zero out data). Bare in mind that this ext.HD is empty, my main one with all backed up data is at another location and is not readily available, and I then get the notice:"Disk erase failed with the error: Posix reports:
The operation couldn't be completed. Cannot allocate memory."
Even though the disk is supposedly empty, I want a clean disk onto which I can back up what's currently on my machine's HD.
"Smart Utility" tells me that my overall Smart status PASSED but still, I wonder if my machine's HD is on the way out.
I attempted to set up "Time Capsule" (I've never used it before since I prefer to manually back up onto my ext. HD) but it tells me that it can't find an Airport device even though my Airport is functioning normally.
Anyway, I just can't use my ext.HD at this time and am totally flummoxed.

That sounds almost EXACTLY like what happened with my HD leading up to its demise. Also Firewire. Same errors in Disk Utility.

I'm afraid both our HDs are completely borked.

reader50 · Jan 6, 2012, 01:09 AM

It's possible the HD has a corrupted partition table. In Disk Utility, select the drive icon. Then click on the Partition tab.

Set the Volume Scheme popup to "1 Partition". Then click on the (Options ...) button and select GUID Partition Table. Finally, click the (Apply) button on lower right.

The drive will get a new partition and format. If the hardware is OK, it will mount afterwards.

ergo · 05:45 AM

I attempted to create 1 partition but the result was the message..."Partition failed with the error: Posix reports:The operation couldn't be completed.Cannot allocate memory".
Maybe the handwriting's on the wall......my machine's HD is toast? With the exception of this ext. HD issue, so far my machine's HD is not showing any other symptoms of failure. It appears to be operating normally, otherwise.

ergo · 02:03 PM

I do believe that I found the reason for the problem and its remedy. I've been using a 6 foot long firewire cable that I purchased not long ago. I decided to try the short cable that came with my ext. HD and whaddya know, the HD icon appeared on my desktop and the HD works just fine without issues....whoopdeedoo! I just downloaded the contents of my machine's HD into my external one without problems.
I suspect that by folding the long cable and jamming it into the rather tight confines of the HD case the woven copper strands broke apart at one of the stress points.
Anyway, I am relieved. Thanks for all the suggestions....I really do appreciate the feedback.

G56Ace · Jan 6, 2012, 04:37 PM

This actually happen to me a few weeks as well. I was able to fix it though, thanks guys.

Mrjinglesusa · Jan 6, 2012, 09:14 PM

Well, following ergo's solution I tried a different, shorter FW cable. No go on my drive. Still failed to format or re-partition. I'm going to try attaching a USB cable in case the FW port on the drive or computer is fried to verify that it's the drive that is the problem. Will report back.

G56Ace, how were you able to solve your issue?

Mrjinglesusa · Jan 7, 2012, 01:33 PM

Originally Posted by Mrjinglesusa

Well, following ergo's solution I tried a different, shorter FW cable. No go on my drive. Still failed to format or re-partition. I'm going to try attaching a USB cable in case the FW port on the drive or computer is fried to verify that it's the drive that is the problem. Will report back.

G56Ace, how were you able to solve your issue?

USB Cable worked! Disk Utility was able to partition and format the drive when attached with a USB Cable. Two different firewire 800 cables failed. Looks like the firewire port on either the drive or my computer is bad.

pendragon · Jan 7, 2012, 04:48 PM

Many thanks for posting the "solution". Indeed, I would not have divined the fix.

Now, if only there were a fix for the FW port. Contact cleaner may help, but please most cautious re shorting, pin bending, etc. And then again, the problem may not even be with the port per-se.