-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 2012-04-05 09:30, Danny Kukawka wrote: >>> We create a new RBD on the cluster, mount it on the client and let fio >>> start it's test on the RBD. The RBD is completely empty at this moment. >>> Not sure what happens if fio reads some random offset that may isn't >>> filled with data at this moment. Or is fio only reading from a prior >>> written block/offset? >> >> OK, if we back up a bit. If you have a workload that is rwmixread=50, >> hence doing equal amount of random reads and writes. Then the job will >> read 50% of the disk, and write 50% of the disk. None of the read and >> write offsets will be the same. So if the drive is initially empty, you >> are reading non-initialized data. >> >> Same thing is true for your workload. So some of the reads you see will >> be the verifies, but some of them will also be for parts of the disk >> that you will then never write. > > We solved it now by running an initial fio write over the full RBD > before running any verify tests: > > fio --name=fill-rbd --filename=/dev/rbd1 --direct=1 --rw=write \ > --bs=4M --size=25g --ioengine=libaio --iodepth=128 > > Now we don't see problems with over-reporting fio anymore. Excellent, so it was down to reading un-written data. Thanks for confirming. - -- Jens Axboe -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQIcBAEBCAAGBQJPfb0qAAoJEPfTWPspceCmzawP/RLbtj62iOVuFJm5rK42Mmq0 Texy8U9RJz4D4h5oc9xAQkvlavBGPWnf0WgsnbkSr7tc/STtqVg5GW6Y8ybvfAkw 2OlZt5T/vb23uz8L9OKp+HCjV6p6Mq7lbksAcddeZdPp9GyzE+v/Cby7LMjIRgjd OPtq759KCb/fr2gWYpxJyyyZlXost1RrRnE+OsnKhThqIYFg42G4IpdmaZGbLeTi 3EeXTNE5RDSplnuu1BsE9jffaTZuTbjm4HbCiMyixXEtp/dZBrS4tlmClC7bpjdt SQMp68wBvji26f7K91JcjENvagGBEmi6SRJxCUgNmmZhKr3Kaf39JzbN9zEPIHOp zOlWomS0D9Qpj0Sh24x81nlQXbWDP0aLmrggH6w5rlqLGl3pq1kz3Wgn+RkwcObw ri8JYy8aVqT5YCVNIriIW5rQCg7kmJp170ZH6YaPd7+SeiifX8ICWFplbKHjF5Vs vnnysT9gYEH0PLqpcoVHaYV2SFKEWVtHo7yvpqsyVevdP6uwFFXg83pAERDPsxcc ro2VOhdJON+AhcgdgUmyfWxfcbDQnpyuw5v3/lMc2LB1oqgfKjXgW6CxqOh+tPmX IUrpomRX+6B4WxPBxCm1Ivpr7Vja9DdFspKBZhRH4i7LErwWKTVMBKv6CaS+zxZn bK8sy3IbjEeGP+Mv+aHs =RYtK -----END PGP SIGNATURE----- -- 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
