Convert FAT32 to HFS+ nondestructively?

April 3, 2006 7:45 AM

Is it possible to convert a FAT32 disk to HFS+ in-place (i.e., with all the data intact)?

I'm talking about a large disk (160GB), not an ipod. I'm guessing the answer is no, but it's worth a try asking.

posted by dmd to computers & internet (8 comments total)

if you have some free space and LOTS of patience, you can resize your FAT32 partition, create a HFS+ at the end of the disk, move some data from fat32 to HFS, resize fat32 again, resize HFS, rinse, repeat.

This is not healthy (specially if you have only 1GB free, you'll have to repeat this procedure 160 times), but you asked if it was possible.

I've done something similar using partition magic and ntfs/ext3. I have no idea if partition magic can do this kind of stuff with hfs.
posted by qvantamon at 7:50 AM on April 3, 2006

I don't believe PartitionMagic supports HFS or HFS+ -- They're listed on the product feature page.
posted by chuma at 8:06 AM on April 3, 2006

This is definitely shady, but I'd be lying if I said I haven't done it once (or twice, or three times...)

When I migrated to a Mac, I wanted to do the same thing. I had a bunch of media on a FAT32 FireWire/USB disk, and I wanted to boot the mini from that drive.

I tried all the kung fu I could, and the best answer I could come up with was "borrowing" an external drive from Circuit City. They had a BIG ad campaign last year (or so) about their "no questions asked" return policy, so I don't feel all that bad.

Just go buy a big one (although I don't see why you'd need over 160 GB), carefully unpack everything, and hook it up. It'll be formatted as FAT32 out of the box (at least mine was). Copy whatever you want to save to that drive. If you're using a Mac, you could use a program like Carbon Copy Cloner to do a bit-for-bit copy of the drive to the external one, as long as you're not booting from it. Once you're sure everything you need is copied over (and I'd test-open a few files to make sure everything copied OK), format the old drive as HFS+. Then, copy everything back over.

When I did this, I held on to the drive for another day or two after I copied everything back just to make sure I wasn't missing anything. After that, pack everything up JUST LIKE WHEN YOU OPENED IT and return it to Circuit City. I couldn't say this for sure, but I'd imagine that they just shrink-wrap it again and stick it out on the shelf and sell it as a new product...
posted by cebailey at 8:48 AM on April 3, 2006

iPartition might be able to do this now, but it's a pretty hard problem to solve reliably. Ask the folks at Coriolis.

I suggest this with the caveat that I tried iPartition once and once only, and it didn't work as advertised.

The easiest thing to do would be to grab another large disk, create an HFS+ filesystem on it, ditto or rsync the files across, and then swap devices (or reformat the FAT device and re-ditto the files back).

If the files are important enough to try to preserve in the first place, they're important enough to back up and restore. That you change the underlying filesystem between the backup and restore options happens to be a bonus.
posted by majick at 8:50 AM on April 3, 2006

Isn't there a 4GB limit per file on FAT32? That would make it impossible for example to store the multi-GB disk image file produced by CCCcloner...
posted by omnidrew at 8:52 AM on April 3, 2006

Umm, if you only have one hard drive and this data isn't already backed up, and you care about the data, you would be nuts to experiment with this. Follow cebailey's advice, but don't just "borrow" a second drive (Hey, and how'd you like to be the sucker that gets that drive "new" the next week? But if you do "borrow" don't forget to do a low-level reformat to make it hard for someone to get at your data when they buy it "new" later on . . .) You can buy a new 200GB external drive for $150 these days, and you should have this stuff backed up anyway. Unless you've got this data backed up, you are describing the blueprint for a disaster messing around with reformatting partitions and so forth. It might work, but if it doesn't, you're dead.
posted by fourcheesemac at 9:07 AM on April 3, 2006

If you follow cebailey's advice, be aware that CompUSA has (I believe) a 15% restocking fee on all non-defective returns.
posted by gd779 at 10:41 AM on April 3, 2006

Yeah, I guess I'll go the "get a swap drive" route.

All of this data is actually backed up redundantly in four locations. The trouble is that those four locations are all at the "bottom" of asymmetric DSL connections - fast for me to back up to, hideously slow to restore from.
posted by dmd at 6:29 PM on April 3, 2006