>> I wonder how many times I saw someone - including myself - fire up >> bonnie++ or iozone with a rather small test file compared to the full >> disk size ... Thanks very much everyone! This was an (overdue) eye >> opener. > In addition, testing with a file is dependent on the state of the file > system. For example, if you're using a 100GB file and there's not enough > contiguous free space to lay it out in one chunk you could have regions on > different parts of the disk. Further, even there is enough space, that space > could be near the inner or outer diameter which would also affect > performance. > > There is a way to get a file address to lba map (which would give you some > insight into how a file is laid out). I think there's a syscall. Jens should > know. Yep, you can use FIBMAP/FIEMAP to walk the extents of the file and get a full map of how it's laid out on disk. Not sure if there are tools that'll do this for you, if not is pretty trivial to write. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
