On Wed, Jul 30, 2008 at 12:08 PM, Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote: > In dstat, the speed is doubled for the total for some reason, divide by 2 > (if you compare with iostat -x -k 1) you should see the difference. Ah, nice catch. It still doesn't change my question. Upon further reflection, I believe I know what has caused the read/write disparity: 1. I've done so much testing with these devices that the contents have been zeroed many times. 2. I am GUESSING that if the raid recovery code reads from drives A, B, and C, builds the appropriate checksum and verifies it, if the checksum matches it skips the write. I believe that this is what is happening. To confirm, I wrote a few gigs of /dev/urandom to one of the devices and re-tested. Indeed, this time around I saw plenty of writing. One mystery solved. Remaining questions: 1. Why does the version of metadata matter so much in a --grow --size operation? 2. There appear to be bugs when a bitmap is used. Can somebody else confirm? 3. I'll look into the awful speed thing later as that doesn't seem to be an issue. -- Jon -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
