Welcome back to Ask TUAW, our weekly Mac troubleshooting Q&A column. This week we've got questions about recovering video files from a corrupt SDHC card, transferring files from an old Mac to a new one, MobileMe sync, virtual machines and more.

As always, your suggestions and questions are welcome. Questions for next week should be left in the comments. When asking a question please include which machine you're running and which version of Mac OS X (we'll assume you're running Leopard on an Intel Mac if you don't specify). And now, on to the questions.

Matt asks:

I recently shot video with a camera that records it to an SDHC card. Unfortunately, that card is now corrupted and when I try to download the video to my computer, it doesn't show up. How can I recover the video from the card?

I know how you feel because this exact thing happened to me recently. We shot a bunch of great video interviews for another site I work with, and one of the SDHC cards became corrupt. Fortunately, all was not lost but recovering the video, at least for me, was a two step process.

This is the method that worked for me, even though there are probably other tools available; I was under a deadline and needed to get this worked out fast so looking for the best free apps or the best deal wasn't an option. However, it did work and all the video was recovered with no loss.

We're back with another edition of Ask TUAW. This time around we've answering questions about iTunes libraries, Mac data recovery, Snow Leopard on older Macs and more.

As always, your suggestions and questions are welcome. Questions for next week should be left in the comments. When asking a question please include which machine you're running and which version of Mac OS X (we'll assume you're running Leopard on an Intel Mac if you don't specify). And now, on to the questions.

Daneel asks:

I'm running OS X 10.5.7 and Windows Vista (via Bootcamp) on my iMac 24". I was wondering if there was any way in which I could make the iTunes apps in both Windows and Mac use the same iTunes library. File access is not a problem as I've got the ntfs-3g driver on the mac side and mac drive on the PC side.

I have my iTunes library on an external hard drive. To make iTunes use this particular folder, I create an alias of the folder on the external drive and replace my iTunes folder located in Users> "User Name" > Music with the alias. iTunes has no problem with this setup.

You should be able to do the same thing in both the Mac and Windows versions of iTunes. Just set an alias of the iTunes folder you want to use in Windows pointing to your Mac iTunes library and you should be good to go.

Back to Part I: losing all the data on a hard disk, and Part II: the trials and tribulations of paying to get it back. Now we find out what happened, and what you can expect from a data recovery specialist.

Greg, the technician from Iomega Data Recovery, sent back two documents two days later: One was a Word document containing a list of files that were recovered from the disk.

The document had most of my files in it, but some were missing. Many of the files were grouped by file type in an "orphans" folder, meaning that the files were on the disk, but their place in the disk's directory structure was lost. Some files were only named according to their file type, such as "m4p-00195.m4p" and "InDesignCS-00003.indd" because their filenames were gone. I would find out later that some files were copied several times (sometimes as many as six times): once as part of the directory structure, and again in the "orphans" folder. Still: many copies are better than no copies.

They offered to return the data on a new hard disk, but the cost of it is not included in the recovery fee. The second attachment to the tech's email was a price list. I chose the cheapest bare hard disk at the necessary capacity, since I had an enclosure to put it in. They offered (more expensive) USB and FireWire hard disks as options for return as well. So add another $55 to the total price.

Greg also asked for a list of the 20 most critical files that could be used as a test for successful recovery. I emailed him a list of mostly files for work I had in progress during the failure, a brochure for a client of mine that manufactures propellers. He called the next day, walking me through the contents of the InDesign document and its support files. "This one appears to be a picture of a propeller blade. This one has a big headline that says 'simply the best.'" Relief. I was satisfied that everything was recovered, approved the recovery, and thanked Greg.

The next part was the hardest: Paying the invoice. The grand total wasn't as bad as I thought: I was prepared to pay tax on all $1,500, but (in California at least) services aren't taxable. So the only tax I had to pay was $4.54 on the replacement hard disk. The grand total was $1,559.54. I'm writing that off my taxes this year.

Once my payment was processed, which took a day, two drives were overnighted to me: the original (failed) drive, and the new replacement drive. I popped the replacement went into my enclosure, and -- tah dah! -- there were my files.

The most significant casualty of the data recovery, however, was the loss of 10 years of painstakingly collected Mystery Science Theater 3000 videos. Many were videos I had recorded originally on VHS, some had been, uh, acquired by other means -- as youthful indiscretions, shall we say. Thankfully, all my project data and purchased music was safe and sound. Everything that was lost could be replaced.

Files on the replacement disk were painfully disorganized, though, which gave me an idea of just how logically corrupted the volume was. Files that were added to the drive after it had been connected via the AirPort Base Station were mostly in the Orphans folder, apparently scattered hither and yon across the disk's platters. I spent the better part of a day copying files, reorganizing everything, and preparing my new backup strategy that included a brand-new, 1.5TB external disk to use with Time Machine.

I learned my lesson the hard way. I had a good experience, but paid dearly for it.

If this story saves anyone any amount of money for data recovery, then it's done its job. Please: Back up your data. The money you spend on a hard disk for backup is far less than what you'd spend on data recovery.

There is no shortage of stories here on TUAW (and elsewhere) that extol the benefits of backing up your data. Apple even makes it ridiculously easy to do so -- with Mac OS X 10.5, Time Machine, a blank drive, and some spare time, you're set.

Nevertheless, despite your best efforts, there are unforeseen circumstances where you might need to utter those dreaded words: "I need to send this for data recovery." Perhaps your airplane landed in the Hudson river, and your waterlogged laptop was stuck with your luggage. Perhaps an external disk is suffering from a manufacturing defect. Perhaps your backup disk is the disk that failed.

Unfortunately, there is no way to sugar-coat this: Data recovery is a painful, patience-trying, and absurdly expensive process. But if it's the only way to recover mission-critical data, it could be your only option.

It was for me.

Back to Part I of Robert's tale of data recovery. It's a typical geek story: Boy gets data, boy loses data, boy tries to get data back.

Because of my former employer's professional relationship with Iomega, I had sent a disk for recovery to Iomega Data Recovery before, and was confident they'd be able to recover the data. I went to their website, and started a quote.

It's worth mentioning that there are many other services besides Iomega Data Recovery that do excellent work. DriveSavers, for example, had a booth at Macworld where people could walk up, physically damage a disk by scratching it, and -- behold! -- they still could recover the data before your eyes. Other services are available from Total Access, as well as from local technicians who can come to your location.

Starting the quote began with asking for my contact information, along with details about the drive. I tried to be as explicit as possible about how the drive was connected, to see if they would be able to isolate the logical failure that happened on the disk, and recover the data accordingly. They also had an area where you could specify specific files or file types to target for recovery.

Submitting the quote generates a document to print include in the box when you send it to them, and tips for packing the drive securely. I wrapped the drive in foam, put it in a snug-fitting box, and sent it to their lab in Santa Clara, California.

Then, the waiting started.

A technician, the supremely helpful and consummate professional Greg Sabanis, emailed me five days later (there was a weekend in there, if I recall correctly) with an analysis of the damaged drive. He said:

The drive has read errors affecting structures and possibly data files. Based upon this evaluation, we feel that a recovery may be possible. We will have to attempt to manually rebuild the corrupted / invalid file system components, mount the recovered volume(s) and finally determine if some / all of the data you require is intact.

That was something of a relief. Then came the sticker shock: The recovery would cost $1,500, plus tax. The good news (I suppose) was that I didn't have to pay it now: I could see the results of their recovery first, and then determine if it was worth it to spend the money for what they recovered. If Greg couldn't recover any data off the disk, there would be no charge.

Speaking with friends, it's clear that Iomega Data Recovery is average in terms of cost for the size of the disk I sent them. Lower-capacity disks, flash media and removable storage costs less. One thing's for sure: they have you by the huevos, and they're gonna charge you for it.

With client work on that drive, the nascent reputation of my freelance business was on the line. I had no choice but to spend the money. So, I signed their evaluation, faxed it back, and hoped for the best.

Part III: The thrilling conclusion.

DiskWarrior, my personal favorite disk repair utility (especially if the problem drive is the startup disk) has just been updated to Version 4.1. The new version is now fully compatible with Leopard (there were some issues with repairing disk permissions on a Leopard startup volume), so if you rely on DiskWarrior as an essential part of your Mac Toolkit arsenal (as I do), you can rest easy.

Alsoft has also introduced some additional Leopard specific repair features in DiskWarrior 4.1. What has me the most excited is the ability to repair directory hard links. Hard-linking is a key part of how Time Machine creates back-ups. How the process works is complicated (although this article does a very good job of trying to explain the whole process), but it is a vital part of Apple's back-up system. The ability to repair directory hard links means that DiskWarrior 4.1 should be able to at least attempt to repair a Time Machine volume. That has actually been my only concern about Time Machine -- what happens if that volume become corrupted or wonky? I hope I don't find out first-hand, but I'm glad some options exist.

Current users will soon be able to download an update CD directly from Alsoft's website that will create a new DiskWarrior startup disc (in the event that the drive needing repair is the startup volume and you don't have access to another Mac). However, please note that the update will only startup the same set of Macs as your current CD. So if your current CD will only boot up to June 2007 MacBook Pros, the update CD will not allow that disc to be used with a November 2007 MacBook.

One other caveat, if you want to run DiskWarrior 4.1 from a version of OS X other than Leopard (say, Tiger), two features will not work. You will not be able to repair permissions of a OS X 10.5 startup disk and you will not be able to rebuild a FileVault created under OS X 10.5. So if you need to repair a Leopard volume, it is best to either run the startup CD or access the drive from a computer that is also running Leopard.

[via MacTech]

Mark Newhouse offers up a problem and a solution today at LowEnd DSLR: A Digital Photographer's Worst Nightmare. What do you do if you've just shot 150 digital photos and your flash card appears to have corrupted the data on it. He reviews several of the solutions that exist for Mac users and, happily, finds a software program that successfully recovered the RAW files from his flash card.