finger-printing raid (redundant array of independent disks)?

http://forums.xkcd.com/viewtopic.php?f=12&t=11699

For an even better example, there are a couple papers on something called "grey-box" testing that came out of UW-Madison that caught my attention when I was looking at grad schools to apply to. Some of the same people worked on both, and they ar both doing grey-box examinations of the storage subsystem. One of them is that they came up with a method and a program that implements that method for figuring out properties of a RAID system. By measuring latencies and transfer rates and such, they are able to determine what RAID level is running, what striping pattern is being used (for instance, for successive blocks on RAID 5, is the parity block on drives 1-2-3-4-5-5-4-3-2-1 or 1-2-3-4-5 or what), etc. We did a similar thing for an intro assignment in my OS class -- we were measuring block sizes of the file system, readahead behavior, and cache behavior. A second paper was describing some firmware that could sit on a disk itself and determine, from the pattern of writes and reads, which blocks represented data blocks, which represented inode blocks, which were journal blocks, and such so that the drive could apply different treatment to each sort. (I forget their suggestions for what you might want to do with the different blocks though, and can't look at the paper because I don't yet have Acrobat Reader installed because this is a fresh system.) If those papers aren't about computers, I don't know what is. -- EvanED