Try to mount a dmg file --> Input/Output error

Question

Level 2

165 points

Try to mount a dmg file --> Input/Output error

I have certainly searched thru postings, but I cannot quite find a solution.

[1] An external FireWire drive holds a lot of dmg files of application installers.
[2] Double-clicking some, not all, of them results in an Input/Output error.
[3] Toast is always able to mount them.
[4] When the error happens, an attempt to copy the dmg file onto the Desktop results in another error message "The Finder cannot complete the operation because some data in "<name>.dmg" could not be read or written. (Error code -365)". At this point, clicking on OK brings up a Copy window which hangs. The only way out is to Force-Quit the FInder.

What should I do to rectify these issues?

MacBook Pro 17-inch (June 2006), Mac OS X (10.5.4), G5 Dual 2GHz Tower (Sept. 2005)

Posted on Jul 28, 2008 7:39 AM

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Answer 1

glsmith

Level 3

875 points

Jul 28, 2008 10:31 AM in response to Kunio Mitsuma

Do you reliably get errors on the same dmg files? Or is it just that sometimes, some of the dmg files show this problem?

If the errors are reliably reproducible, if you first copy the file to your local machine, then double-click it, do you still see a problem?

Have you ruled out problems with your external disk, like bad sectors? Anything in your system.log that might give us some more clues?

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Answer 2

Kunio Mitsuma Author

Level 2

165 points

Jul 28, 2008 12:34 PM in response to glsmith

[1] When a dmg file does not mount
When double-clicking on a dmg file produces the "Input/Output error", subsequent attempts to double-click on the same dmg file *may or may not* mount it. That is the puzzling thing.

[2] Finder copy fails
When a dmg file fails to mount with the "Input/Output error", an attempt to duplicate the same file on the same disk produces the *error code -36* though the file is indeed duplicated.
If I try to copy the file onto the Desktrop, it results in the same *error code -36*. But, in this scenario, I have to Force Quit the Finder to terminate the copying.
According to http://support.apple.com/kb/HT1618, the *error code -36* means *I/O error (bummers)*. But, I do not know what this error implicates.

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Answer 3

glsmith

Level 3

875 points

Jul 28, 2008 12:34 PM in response to Kunio Mitsuma

[1] When a dmg file does not mount
When double-clicking on a dmg file produces the "Input/Output error", subsequent attempts to >double-click on the same dmg file may or may not mount it. That is the puzzling thing.

Ok, so it doesn't sound like always have the same problem with the same dmg files.

[2] Finder copy fails
When a dmg file fails to mount with the "Input/Output error", an attempt to duplicate the same file on the same disk or copy it onto the Desktop fails with the error code -36.
What is the error code -36?

That error code just means "I/O Error", which we already know. Have you verified that your external disk is healthy, like with disk repair?

It sounds like the disk has some bad spots, and is intermittently causing I/O errors. Sometimes the bad sectors get repaired, which is why subsequent attempts to mount likely succeed.

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Answer 4

Kunio Mitsuma Author

Level 2

165 points

Jul 28, 2008 12:41 PM in response to glsmith

Yes, I have used both Disk Utility's Repair Disk and DiskWarrior.
Both utilities report that the disk appears to be OK.

Should I use another disk utility such as TechTool Pro?

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Answer 5

orangekay

Level 5

4,085 points

Jul 28, 2008 1:38 PM in response to Kunio Mitsuma

If the drive is testing healthy then I'd try different ports/cables/enclosures in that order.

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Answer 6

Kunio Mitsuma Author

Level 2

165 points

Jul 28, 2008 2:43 PM in response to orangekay

I appreciate your suggestions.
The external drive in question is OWC's Mercury Elite-AL Pro with FireWire 800 (2) and 400 (1) ports
It was purchased in February, 2008. Its original connection was thru FireWire 800 to my G5 Tower.

[1] Ports
The G5 has only one FireWire 800 port, while the OWC enclosure has two.
So, I used the other FireWire 800 port on the OWC.
The same intermittent I/O error in mounting dmg files.

[2] Cables
I tried another FireWire 800 cable with either of the two FireWire 800 ports on the OWC.
The same intermittent I/O error in mounting dmg files.
So, I switched the connection to FireWire 400 between my G5 and the OWC.
No I/O errors after trying to mount numerous dmg files.

[3] MacBook Pro
I disconnected the OWC and connected it to a MacBook Pro's FireWire 800 port.
No I/O errors after trying to mount numerous dmg files.

From [1], [2], and [3] above, can I deduce that something is wrong with the FireWire 800 port on my G5 Tower? I thought that both FireWire 800 and 400 ports on the G5 Tower were controlled by the same chip.

Please advise.

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Answer 7

orangekay

Level 5

4,085 points

Jul 28, 2008 2:53 PM in response to Kunio Mitsuma

It could be bad or it could just be incompatible with the enclosure's bridge.

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Answer 8

Kunio Mitsuma Author

Level 2

165 points

Jul 28, 2008 3:13 PM in response to orangekay

The FireWire 800 connection between my G5 Tower and the OWC drive worked without any issue between February 2008 and yesterday. So, I believe we can rule out incompatibility.

But, how would one 'test' a FireWire 800 port?

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Answer 9

orangekay

Level 5

4,085 points

Jul 28, 2008 3:23 PM in response to Kunio Mitsuma

You'd have to take it in. If it is indeed bad I believe they have to give you a whole new logic board.

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Answer 10

Kunio Mitsuma Author

Level 2

165 points

Jul 28, 2008 3:28 PM in response to orangekay

You mean, the Genius Bar, for example?

Since the G5 Tower was bought in September of 2005, it would not make financial sense to opt for a new logic board. Maybe this is a writing on the wall that I need a Mac Pro then.

Ouch!

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Answer 11

orangekay

Level 5

4,085 points

Jul 28, 2008 3:31 PM in response to Kunio Mitsuma

They won't actually be able to test the port at the Genius Bar, but they will be able to send it in (after quite a bit of arguing no doubt). You can also look around for an Authorized Service Provider in your area, though Apple goes out of their way to make sure nobody ever finds them.

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Answer 12

Kunio Mitsuma Author

Level 2

165 points

Jul 29, 2008 4:34 AM in response to orangekay

It just occurred to me that, instead of fooling around with Apple, I could simply add a PCI card with FireWire 400/800 ports on it.

I am assuming that, even if something may be wrong with the FireWire 800 port on my G5 Tower, it would not affect the ports on the add-on PCI card.

Am I correct?

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