Internal Time Machine "looking for backup disk" (not time capsule)

Question

Hello,
I have the infamous "looking for backup disk" issue. My Time Machine drive is an internal drive, NOT a time capsule. It is mounted and visible, and the backups show up on it in the Finder. When I select to enter the Time Machine "starfield" UI, all my previous backups are browsable. But when it comes time to actually back up... it just says "looking for backup disk" forever. I've tried leaving it like that for something like 40 minutes, no joy. This is not a huge disk, there are about 700 GB of backups on it. The HDD activity light on my computer is NOT showing any activity when I am idling but it is "looking for backup disk," so I don't think it's scanning the drive or anything.
I have tried turning TM off and on, removing the drive and re-selecting it, unmounting it and remounting it, deleting the TM preference plist file from the library, rebooting, and all manner of combinations thereof. Nothing seems to work.
Anyone have any advice? This is on OS X 10.8.2 by the way. The TM backup worked fine through 10.8.1 and 10.8.2 with no problems until now. I don't recall doing anything specific to mess up TM or the disks in any way, although I may have turned TM during a reboot cycle prior to this happening (don't recall if this is actually the case, but in any case it shouldn't have caused such an error, no?).
Thanks in advance,
—Gabriel

Answer 1

[Just a note, TM only works on OS X Journaled drives (i.e. HFS+ drives). TM does not back up your FAT drive.]
Isaac:
If you unloaded the NTFS and FAT kexts, your TM backups might (might!) work again, but of course in that case you would not be able to see your FAT or NTFS drives in OS X, and if you removed the FAT kext then a lot of USB keys would be unreadable in OS X - not a good solution.
The kexts are specific to OS X, so removing them should not affect Windows... but may affect boot camp, I don't know how boot camp is programmed (which would be a problem). Luckily if your Windows drive became inaccessable from boot camp with removed kexts, it should be easy enough to simply boot back into OS X, restore the kexts, and then Windows should work again.
I would recommend not mixing partition types on drives with shared OSX/Win functions, it seems to "tempt fate" as it were with possible errors. I don't know what has precipitated this error in your case, if it was the MSE or disk error or something else, and unfortunately I don't have a real fix to offer beyond trying things with the kexts removed and seeing if they work.
NOTE THAT THIS IS AT YOUR OWN RISK, messing with kexts is not a very recommendable practice since these files enable core functionality in the OS. Make a backup before if you can, and consider your options carefully. In OS X, navigate to /System/Library/Extensions and you'll find a bunch kext files. The two you need are msdosfs.kext and ntfs.kext. Copy ntfs.kext into a backup folder (e.g., on your desktop). Delete the original ntfs.kext from the S/L/E folder. Reboot and see if you can still access windows. If so, reboot into OS X and see if Time Machine works again. If you're good on both those points, then consider going without ntfs.kext on a permanent basis – it is rare that you need to read an NTFS drive while in OS X. On the other hand, if this does not fix your problem, you may try restoring ntfs.kext, and backing up / deleting msdosfs.kext to see if THAT is the culprit. Unfortunately, if msdosfs.kext is causing the TM error, you're kind of out of luck, since going without FAT access will be pretty annoying any time you need to use a drive to swap files between Windows and Mac (using a USB key).
Ultimately I don't have a solution, as I have noted, so much as I've narrowed down where the error is occuring in some peoples' cases (like my own). Good luck!