-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 I recently picked up a Thermaltake BlacX Duet dual drive esata dock and I am having some performance problems trying to use both drives concurrently. The link is running at 3 Gbps both to the PMP and from there to each drive. An individual drive pulls ~175 MB/s, but trying to use both drops to ~60 MB/s each. This is with a simple sequential dd to /dev/null with a 1 MiB block size. Oddly, disabling NCQ results in an increase to ~80 MB/s per drive. I wouldn't think that NCQ would really help for a sequential read, but it certainly shouldn't hurt. Now it does seem that my intel ahci chipset does not support fis based switching, but it doesn't seem like that should make a whole lot of difference for sequential IO since while you are busy sending commands to one drive, the other should still be performing its own readahead into its cache and be ready to satisfy the request quickly once the first drive finishes. How can this behavior make sense? Any ideas on other things I could try? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCgAGBQJTWHoaAAoJEI5FoCIzSKrwgY4H/jIJw7EC8Oh6eXqNma67tVfn eNYgjKOKv1qsn4QDAva1F6TyUdmTzeKVoym4yxOgu51hPzcnPCoeOyOg0ZNNbOSa QSUxWHfgeGVHQvn5j30AZDqbfyIXd062mAjwDndFl4QSYRmAsZmijRavR33bZ8LP S81myeHoRSSIJNJDkRAXtiJckUxjU8HdDkLzvowGCcvgn6MNi6uMtaNepdCOGD5V 9u91uUB7HcsrfBCPutSW3Yv1GoSn4wEPL0/lIzqfP0q81qErsWjXkjqi8VEYXPys FcNT4lSGH0isjSCBtatDYMaWolLsOdkeZW4gwx07WyvsOP4H5fKFpVNrkFoAjoE= =X8IN -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
