So, I had a fun time throwing together a utility last weekend. I thought I'd share it sooner rather than later. I found myself wanting to backup a copy of an ancient ~75g ext3 file system. I got frustrated by of our utilities which don't saturate storage. I wanted dd line rates but I also only wanted to copy referenced data. So I threw something together which does that. I made it work roughly like tar so that people have some idea what to expect. So you can do something like: $ bdar -cf - /dev/sda3 | gzip -c > /tmp/sda3-backup.bdar.gz ... $ zcat /tmp/sda3-backup.bdar.gz | bdar -xf - /dev/sda3 and it will do exactly what you would guess it would do after reading those command lines. The bdar file format is just a header and then a series of regions of bytes described by their length and offset. To create a bdar file from a file system bdar needs to know enough to figure out what extents are referenced. Restoring a bdar is generic, though, it just stamps bytes into the target file. I only taught it the most basic knowledge of ext[234]. Just enough to show that generating the bdar is ~4x faster than tar and ~2x faster than dump :). There's still some available disk bandwidth to consume with read-ahead, but it's pretty close. (single spindle, ~5g of kernel trees, beefy cpus.) I'm going to continue hacking this into something which could be trusted with data but not on any rigorous schedule. I thought I would put it up for others to get a look at and, hopefully, contribute to. There's a lot of fun stuff we can do. It's in a mercurial repo: http://www.zabbo.net/hg/bdar $ hg clone http://www.zabbo.net/hg/bdar ; ls ./bdar Let me know if you give it a try, I'm interested in all feedback. - z -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
