On 12 Jun 2007, Jon Nelson told this: > On Mon, 11 Jun 2007, Nix wrote: > >> On 11 Jun 2007, Justin Piszcz told this: >> loki:~# time dd if=/dev/md1 bs=1000 count=502400 of=/dev/null >> 502400+0 records in >> 502400+0 records out >> 502400000 bytes (502 MB) copied, 16.2995 s, 30.8 MB/s >> >> loki:~# time dd if=/dev/raid/usr bs=1000 count=502400 of=/dev/null >> 502400+0 records in >> 502400+0 records out >> 502400000 bytes (502 MB) copied, 18.6172 s, 27.0 MB/s > > And what is it like with 'iflag=direct' which I really feel you have to > use, otherwise you get caching. I have little enough memory on this box that caching is really not significant :) With iflag=direct I get, um, loki:/var/log# time dd if=/dev/md1 bs=1000 count=502400 of=/dev/null iflag=direct dd: reading `/dev/md1': Invalid argument 0+0 records in 0+0 records out 0 bytes (0 B) copied, 0.0324791 s, 0.0 kB/s real 0m0.085s user 0m0.000s sys 0m0.000s so not exactly ideal. -- `... in the sense that dragons logically follow evolution so they would be able to wield metal.' --- Kenneth Eng's colourless green ideas sleep furiously - 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
