Hi, On 8 April 2016 at 21:01, Foley, Robert <robert.foley@xxxxxxx> wrote: > > Suppose at time A we wrote out a pattern using the parameters above. Later at time B we would like to write the same blocks (offsets) of the test area but with a different pattern of data bytes. Our understanding is that randseed will seed the generation of both a) the pattern of I/O blocks that we generate as well as b) the pattern of data in the buffers we are writing. In other words since the randseed controls both a) and b), there is no way for us to get a different data pattern written to the same pattern of blocks (offsets). You could always force a particular pattern to be put into every block by using verify_pattern (https://github.com/axboe/fio/blob/fio-2.8/HOWTO#L1407 ) and use its %o option for generating more sophisticated patterns. Another choice would be to change the block size otherwise you're going to struggle to work out what "run" the pattern in the block came from. > Does anyone know how to accomplish this with fio? > > We had some ideas around how to solve this if it is not currently supported. It might be useful to have an optional "verify_io_stamp" parameter, which would specify a simple 32 or 64 bit integer that could get added to and verified with the verify_header. Might you be able to do this by creating a particular verify pattern and specifying a custom format using %o? -- Sitsofe | http://sucs.org/~sits/ -- 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
