USB Drives Not Recognized / Mounting | maho

Tag: USB drives not recognized / mounting

USB drives not recognized / mounting

July 20th, 2010

Hi All,

This just started happening within the past month or so. None of my USB drives are being recognized or mounted. They appear within Disk Utilities and I can verify and run checks on them, but they do not mount. This isn’t limited to one device or any specific port. It happens with USB memory sticks, external Maxtor drives (two different ones) and now my Canon PowerShot camera. Basically anything the Mac would mount as an external drive has this issue, so I know it’s not specific to any hardware.

I do have a work around that I found on — If I reboot with the device plugged in and hold the ‘command’ key the drive gets mounted. Next time I try the device though (in the case of my camera plugging it into another computer) it’s not recognized again. I basically have to do this reboot procedure any time I want to use any device.

Any ideas? I’ve searched and found a thread that sounds like my issue, but the OP didn’t post any resolution:

This happens on the MacBook Pro in my signature running the latest OS X (fully patched / updated).

Thanks -


Answer:Have you tried an SMC reset yet?

Answer:Have you tried an SMC reset yet?

No, I haven’t. Good idea. I’ll try that right now.

Answer:Have you tried an SMC reset yet?

No, I haven’t. Good idea. I’ll try that right now.

I had high hopes, but unfortunately, no, that didn’t change anything. I also thought it might relate to the Paragon NTFS driver I had installed too (although this had been there for quite some time), but I removed that and it made no difference either.

I’ve also used Cocktail to remove all system caches, purge logs and reset file permissions. No changes there either.

Again though, rebooting while holding ‘command’ allowed iphoto to recognize and mount my PowerShot SD770 IS after having taken pictures all weekend.


Answer:I am having the same issue. I have a USB mounted drive that is partitioned into drives, one for Time Machine and one for raw video. I have never had a problem until this week. Now I cannot get the video partition to mount. I have tried a reset, verify and repair of the drive and the partition. Nothing! So what update in May caused this crap?!

Now for my rant…

I work in IT, and the reason I switched to the mac was because every night I would come home and have to fix my PC before I could use it. It has been years since I have had regular issues with my home computer. But the last two months have been hell!

Thanks to these forums, I finally figured out the video artifacts I have from time to time are a heat issue and related to my version of the iMac. They come and go, but in April my computer basically became unusable, and now I have to use smcfancontrol to cool my iMac.

Since then, I have had issues every night and cannot trace it to any one thing. I have used Onyx to clean and purge stuff (something I have not done in years), and even purchased the latest MUPromo to get TechTool Pro. (<— what a joke of an app that is). Now this starts this weekend. Of course it is the first time I rebooted since the last update was installed. I am going to pull out an old drive that I have an image on and see if I can reset to that image and if things improve. I would blame my hardware, but all tests are running clean. Most advance operating system… my rather soft behind.

Answer:TTP is a load of poo. Drivegenius is a much better utility for the tool box.

So it sounds like you can mount one of the partitions but not the other? Can you access it with any utilities at all (disk utility? any file recovery stuff?) of is not recognized by anything?

Answer:I found this in System.log

Jun 7 14:45:50 iMac24 kernel[0]: jnl: disk1s1: open: journal magic is bad (0×0 != 0×4a4e4c78)

Looked about and a found a thread on MacNN. Journaling is bad on this partition and this partition only. Just happens to be the partition that I tired to install TTPro’s "magic disk" or whatever the heck it is called. Probably the first time I have rebooted, or unmounted the drive since I tried that and watched it fail.

So you can still get to the data on the drive, IF you can just get the thing to mount. Some have mounted such drives in OS9. But, if the drive is not totally hosed, you can force Journaling off on that partition and then get it to mount. Once you have your data off the device, Re-partition, etc.

The instructions to shut off Journaling, that I found, were missing the force option. See transcript from my Terminal session below. As I write, I am copying my RAW video to another external drive. Once that is done I will ensure that drive is still good before I partition the bad drive again.

iMac24:~ troywill$ diskutil disableJournal

Disk Utility Tool

Usage: diskutil enableJournal MountPoint|DiskIdentifier|DeviceNode

diskutil disableJournal [force] MountPoint|DiskIdentifier|DeviceNode

Enable or disable journaling on an HFS Extended volume. The volume will be

temporarily mounted if necessary, so normally this works whether or not the

volume is mounted. The force option, however, causes a direct write to the

on-disk volume data, and requires that the volume not be mounted.

Ownership of the affected disk is required.

Example: diskutil enableJournal /

iMac24:~ troywill$ diskutil disableJournal force /dev/disk1s1

Journaling has been disabled for volume Video Agent on disk1s1

iMac24:~ troywill$ diskutil mount /dev/disk1s1

Volume Video Agent on /dev/disk1s1 mounted

iMac24:~ troywill$

BY THE WAY, I buy pretty much all my software from MUPromo through the MacRumors link. The little bit I can-do for the help these forums provide.

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