On Wed, Jul 04, 2007 at 08:17:35PM +0400, Michael Tokarev wrote: > Dan Aloni wrote: > > On Thu, Jun 28, 2007 at 02:51:58PM +0400, Michael Tokarev wrote: > >> [..] > >> Test machine was using MPTSAS driver for the following card: > >> SCSI storage controller: LSI Logic / Symbios Logic SAS1064E PCI-Express Fusion-MPT SAS (rev 02) > >> > >> Pretty similar results were obtained on an AHCI controller: > >> SATA controller: Intel Corporation 82801GR/GH (ICH7 Family) Serial ATA Storage Controller AHCI (rev 01) > >> on another machines. > > > > Are you sure that NCQ was enabled between the controller and drive? > > Did you verify this? I know about some versions that disable NCQ > > support internally in their firmware (something to do with bugs in > > error handling). > > The next obvious question is: how to check/verify this? On the lowest level, it's possible using a protocol analyzer. If you don't have one, you need to be familiar with the controller's driver or its firmware. If the driver is based on libata, I think it's possible to get this information easier. Otherwise, such as in the case of mptsas, it can be completely hidden by the firmware. -- Dan Aloni XIV LTD, http://www.xivstorage.com da-x (at) monatomic.org, dan (at) xiv.co.il - 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
