Ok, I have a 250 GB drive. I want to back up two 120 GB drives onto it using the dd command (backing up my TiVo). If I format the large drive with ext2, will it take up more than the extra 10GB (even if I set the block size to 4096)? If so, is there some other way to get this to fit onto the drive? I guess I could dd into the raw drive itself, and give it starting positions and sizes, but it seems like it would be too easy to mess up. Thanks.

I'm using reiserfs for my mythtv box. I wouldn't claim it's the best file system for large files. That's too much like arguing about Linux distros.

I can however show you how much overhead there is on my drive. I have a raid device with 720254976 1024 byte blocks. 720232988 of those 1024 byte blocks are available for files. Of course each directory and file has an additional small overhead, but that shouldn't be a problem in your case. Overall, if I just made one huge file on it, I'd get to use 99.99% of the space. That should be good enough for what you want.

Another option is to partition the drive, and dd into the raw partitions. It's slightly safer than dd'ing into the drive itself, but not much.

use ext3, it recovers from almost any corruption

ext2/3 filesystems by default reserve 5% for root use. Since this is a data drive you can reduce it to 1% or even 0%. So that will save you the 10 GB.

reiserfs v3 is better for lots of small files and xfs is better for many large files. jfs is in between and I haven't tried reiserfs v4 yet.