Why does my external drive mount as not writable?

I've got a 1 TB external WD drive formatted as Mac OS Extended. After upgrading my MacBook Pro this drive occasionally is mounted as read-only. If I open Disk Utility and Verify the volume, the verify completes without reporting any errors, and when it remounts the volume, it's writable again. Anyone else seen this behaviour?
-Brian

You may try a SMC reset, maybe do it 2-3x.
SMC RESET
Shut down the computer.
Unplug the computer's power cord and all peripherals.
Press and hold the power button for 5 seconds.
Release the power button.
Attach the computers power cable.
Press the power button to turn on the computer.

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Why does the external drive not show up on the desktop.

My wife has a G5 (iSight). When we turn on the external drive it does not mount. We have tried restarting the iMac with the external drive on and it still does not show up. What is the problem and what is the fix?
Thanks

Is it by chance a WD MyBook? They are known for problems like that. Could be the cable -- try a different one. Or it could be the Firewire port on the computer. Try a different port on the computer or on the external, if it has one. Have a look at this Apple article with other troubleshooting steps.
http://support.apple.com/kb/HT1151
Message was edited by: WZZZ

Why does my external drive disappear from my desktop?

I am switching from PC to Mac. I have 2 externaldrives. Both have been formatted in FAT 32 by the MAC. When I plug them in the desktop and finder see them, then with both of them they have disappeared from the desktop and from finder. Still can be seen in disk utility and system profiler. How can I find them and why does this happen?

If you daisy chained then try without. May not be enough power to handle both at sme time. Other than that read some info:
1. Shut-down your Mac, and unplug the power cord
2. Turn the power off on your external FireWire devices
3. Unplug the FireWire devices from the Mac
4. Wait for 5 min.
5. Plug the power cord to your Mac only
6. For PPC Macs: Restart the Mac while holding the Option-Apple-O-F, and keep holding until you get the ">" prompt, then release the keys
7. At the ">" prompt type:
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      set-defaults and hit the Return key
      reset-all and hit the Return key
the last command will restart your mac
8. Shut down your Mac
9. Connect all your FireWire devices to the Mac and turn them on
10. Restart your Mac.
All your FireWire devices should reapear, if not repeat the procedure
How to avoid the issue :
The only really proven way to avoid burning up a FireWire port is to connect all devices and to turn them on PRIOR turning on the Mac. Likely, one must unplug them and turn them off AFTER the Mac has been turned off. If you need to connect another device, then you're on for a shutdown of your machine...  It's a tad annoying but it guarantees that the FW ports won't be damaged.  Be careful when using self powered devices such as webcams, iPods, hard drives or hubs, as they can destroy the port pretty easily. Another thing is to avoid daisy-chaining hard drives.
When the FW port doesn't respond anymore :
In this case, peripherals won't be mounted upon plugging, and won't be displayed in Apple's System Profiler. The self powered devices will still be fed by the port, but won't respond either.  It happens that the PHY just hangs after a surge or a random problem. Once hung, the port will not respond any longer, it is possible to reset the component by going through the following steps :
1° boot the PPC mac in Open Firmware by holding [ Apple key - Option - O - F ] after the startup chime.  2° you'll get to a command prompt. the keyboard mapping will be QWERTY, so pay attention when you type the following :  RESET-NVRAM (enter)  RESET-ALL (enter)  3° Now the mac should restart itself and the port should function properly again.  If it still doesn't work, then it means that the PHY is damaged.
http://www.hardmac.com/articles/16/
From Kappy post:
922 is only used in dual drive cases to provide a "build-in firmware RAID support"
912 or 912+ is FW800, the "+" means USB2
911 is FW400
924 adds eSATA support along with FW400/800
MacSales, OWC Tech Support library is where I would go first, as they do tend to have or links to, firmware updates for Oxford.
From Wiebetech:
I just upgraded my Mac OS, and now I'm having trouble with my FireWire device. What can I do?
A: With nearly every OS update Apple releases, some external drives are not recognized after the update. The typical symptom is that the device will not mount but the volume is visible and grayed out in Disk Utility. This means that the device is working properly, but the OS does not recognize the volume as mountable. Sometimes the drive does not show up at all.
The first thing to do is to see if repairing Permissions with Apple's Disk Utility First Aid feature solves the problem. If not, try repairing the disk with First Aid. Another possible solution is to zap the PRAM. This is done with a keyboard command while rebooting. Restart your computer and hold down the Command, Option, P and R keys. Consult the Apple web site for details.
If this does not work, then try pushing the PMMU reset button on the logic board. Consult the Apple web site for locations of the button for your Mac. If the drive still does not show up, shut down, disconnect all peripheral devices, and boot from the Mac OS Installation CD. The later the OS version, the better. Do not reinstall the OS, but when the Installer is loaded up and ready to begin, go to the File menu and use the Disk Utility program. Connect the drive that is having problems, then start the Disk Utility application. If you see the external drive and it is not grayed out, you know the drive is okay. Run Disk First Aid on it anyway. Then run it on your internal boot drive while you are at it. When done, unmount the external drive and UNPLUG it! Then restart the Mac.
When the Mac has restarted and is running on the internal boot drive, reconnect the external drive.

Why does my external drive disappear on restart and i have to keep unplugging and plugging it back in

i just purchased an iMac. i plugged in my external usb drive with all my data and images on it and it shows up on the desktop. It opens and I can see all my files. If I restart the computer for any reason, the drive icon disappears from the desktop and finder. I have to unplug it and plug it back in before it can be seen.

You may try a SMC reset, maybe do it 2-3x.
SMC RESET
Shut down the computer.
Unplug the computer's power cord and all peripherals.
Press and hold the power button for 5 seconds.
Release the power button.
Attach the computers power cable.
Press the power button to turn on the computer.

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Then why does my external HD come alive more frequently? It seems to come on every 10 mins or so for a few minutes - and I don't know what it's doing. (It's not performing a TM backup.)
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I have an external NAS drive with RAID, where I keep ALL my data, because I use number of ways to access them. I also have my photos there. I recently bouht MAC MINI and I want to use it to organise my photos. Because I have only 80G drive on MAC, I choose to import the photos from the external drive to iPhoto, NOT copying them to it's own library but rather referencing them only.
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J.
What I need is to delete the file when I "look" at it,
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You ask a question:
But I am still wondering why isn't there any setup option to actually allow iPhoto to delete referenced files.
and the answer
I know it may cause some problems for some user,
iPhoto is firmly focussed on the home user with a point and shoot camera. It’s very effective at what to does, but it does very simple things. Any setting that could lead to inadvertent data loss is avoided. (There are occasional posts on the forum from folks who uncheck that ‘Copy Files to Library on Import‘ setting but who then don’t actually move the files from the camera. They wonder why iPhoto has “lost their photos“.)
You mention that you’re using the NAS so that access your photos in a number of ways. IF you can tell us what ways you use, perhaps we can help.
I just need to know which directories I imported to iPhoto.
How are these directories organised? Named?
Regards
TD

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Why does my external drive mount as not writable?

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