[dimension10]

The power cord on my external firewire drive popped out while the drive was mounted. When I plugged it back in, one of my partitions on my drive would mount but the other wouldn't. I ran disk utility and the name of the drive still comes up but is greyed out. I ran disk first aid and repair and it said that the disk is fine, but when I click mount nothing happens.

Could anyone give me some advice on how to get the drive to mount again.

[finknottle]

You probably did this but when I had that problem I rebooted and that worked...

[dimension10]

no such luck for me. It's frustrating because it looks like the disk is intact

[reader50]

What is your operating system, 9 or X? If the driver partition took some damage in 9 there are ways to work around it.

[dimension10]

It is in X

[reader50]

Diskwarrior or TechTool Pro is recommended. From what I've read, Norton Disk Doctor is strange and unreliable.

FSCK might be able to fix it, but I've never tried to run FSCK on a volume that isn't mounted. You will need the device ID for that partition, but at least under 10.2.8, neither Disk Utility nor Apple System Profiler privide device numbers. Try this: open Console and Disk Utility. Tell Disk Utility to mount the missing partition, then watch Console to see what the device number is on the failed mount operation. It's most likely going to look something like this: disk0s13 along with an error message.

In Terminal type:

fsck -p /dev/disk0s13

... or whatever the device number is for the bad partition. You may need to run FSCK several times before it completes without finding anything.

If it hits more serious errors, it will ask you to run it manually (without the -p flag):

fsck /dev/disk0s13

... or whatever your device number is. FSCK will find errors and ask permission to proceed at various points. Again, you may need to run FSCK several times to get a clean bill of health.

Afterwards, try again to mount the partition from Disk Utility, or unplug/plug the external drive, or reboot. Hopefully it will mount and appear.

[dimension10]

thanks, I have tried to run disk doctor twice and I got the beach ball. What exactly does fsck do? I am not all that handy with UNIX commands.

[reader50]

FSCK = File System Check
It is the *nix equivalent to Apple's Disk First Aid. Whenever OSX boots up, FSCK is run on the boot partition before bootup is completed. However, so far as I know, it only checks the boot partition. To do another partition, you need to fire it up manually.

Disk First Aid will refuse to fix 'dangerous' or complicated problems that may result in data loss. FSCK is willing to make the harder repairs, it will ultimately do whatever it takes to fix the disk. Disk Warrior or TechTool Pro are better, especially at recovering files, but FSCK is free.

[dimension10]

is this really bad news?

Welcome to Darwin!
[] mike% fsck -p /dev/disk3s12
/dev/rdisk3s12: BAD SUPER BLOCK: MAGIC NUMBER WRONG

/dev/rdisk3s12: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
/dev/rdisk3s12: [] mike% fsck /dev/disk3s12
** /dev/rdisk3s12
BAD SUPER BLOCK: MAGIC NUMBER WRONG

LOOK FOR ALTERNATE SUPERBLOCKS? [yn] y

SEARCH FOR ALTERNATE SUPER-BLOCK FAILED. YOU MUST USE THE
-b OPTION TO FSCK TO SPECIFY THE LOCATION OF AN ALTERNATE
SUPER-BLOCK TO SUPPLY NEEDED INFORMATION; SEE fsck(8).
[] mike%

[reader50]

I don't really know, but I think you should get DiskWarrior. FSCK seems to be saying that it can't interpret the partition - ie HFS, HFS+, DOS, interleave, directory offset, virtual block size, etc. This data is usually recorded in the first block, so software will know how to interpret the rest of the partition.

Without critical formatting info, FSCK doesn't know what to do next. DiskWarrior or TechTool Pro are specifically designed to HFS/HFS+ and should be able to recreate that block. In HFS at least, the start block is duplicated at the very end of the partition.

[dimension10]

I really appreciate the help on this. What a nightmare.
I tried to run diskwarrior, but I get the beachball.

What part of tech tools should I run? The disk appears fine in Apple Disk Utility, so I don't want to run something drastic that will kill the data on the drive.
I don't have a drive big enough to back up all my data on to, do you know if there is a utility within Tech Tools that will allow me to make the drive mountable again, without having to back up and reformat it?

[dimension10]

The busted partition doesn't seem to be displaying under the Volumes tab in tech tools.

[dimension10]

WHOA, booted in 9 and the drive mounted. Ran first aid and now it mounts in X again

[reader50]

There should be a command to "Search for missing volumes". There is in TTP 3 (OS9).

Edit: Yes, going after it in 9 often opens additional options. Solving problems is one of the big reasons to maintain an OS 9 boot option, many people seem to think it's preferable to delete their OS9 resources.

[tooki]

reader50, you DO realize that in OS X, when you run Disk First Aid, it's actually running fsck, right? Both the fsck command (under any *nix) and OS X's Disk First Aid are just front-ends: they determine the correct disk utility for the filesystem and run it. For example, if you run fsck/DFA on an HFS volume, then the process fsck_hfs is launched, which actually performs the repair.

It IS true that fsck can be commanded to do things that DFA won't do, such as work on some unmounted volumes.

tooki

[reader50]

DFA in OSX does use FSCK to do file scans and repairs. However, DFA in OS 9 most definitely does not. It's code predates OS X on the Mac.

Since the behavior of FSCK is different from DFA on OS X, it is useful to consider them separately. The DFA interface is 'safer', the direct FSCK interface offers those extra options. It didn't seem important to distinguish that when someone was asking for help.

Edit: fsck_hfs (a separate *nix command) was what was needed, rather than plain fsck. It's a pity the fsck man page never mentioned fsck_hfs, I didn't find it until tooki mentioned it.