Re: Some NCQ numbers...
From: Dan Aloni <hidden>
Date: 2007-07-04 16:45:23
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linux-scsi, lkml
On Wed, Jul 04, 2007 at 08:17:35PM +0400, Michael Tokarev wrote:
Dan Aloni wrote:quoted
On Thu, Jun 28, 2007 at 02:51:58PM +0400, Michael Tokarev wrote:quoted
[..] 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