Date: Mon, 02 Mar 2009 12:44:10 -0700 From: Scott Long <scottl@samsco.org> To: Josh Paetzel <josh@tcbug.org> Cc: freebsd-scsi@freebsd.org Subject: Re: twa driver and 3ware 9690SA issues Message-ID: <49AC370A.1040700@samsco.org> In-Reply-To: <09CE3D22-431A-433F-9CAF-6896FF77DDB1@tcbug.org> References: <09CE3D22-431A-433F-9CAF-6896FF77DDB1@tcbug.org>
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Josh Paetzel wrote: > This is somewhat of a repost from questions@, and I'm currently engaged > with 3ware about this issue. > > I have several 3ware 9690SA SAS RAID controllers. This item is very > similar to their 9650SE controller. It uses the same firmware and > driver, the difference being it can handle SAS drives. Up until this > point all of the arrays we've used with these drives have been RAID 1 > arrays with 7200 RPM SATA drives, but recently we've started using > 15,000 MBA series Fujitsu SAS drives in places. > > The arrays have always been detected as: > > da0: <AMCC 9690SA-4I DISK 4.06> Fixed Direct Access SCSI-5 device > da0: 100.000MB/s transfers This 100.000MB/s number is fictitious. The driver is just filling in a dummy value. Filling in the real number would require the driver being able to query the card for the negotiated bus speed. I have no idea if that's possible for TWA given the programming information that is public for the card. > > Which wasn't that much of an issue, as SATA drives aren't capable of > sustained sequential 100 MB/sec transfers anyways, but the SAS drives we > are getting are supposedly capable of 180 Megs/sec and I'm not seeing > it. I'm unsure of how to eliminate caching from the equation, simple > tests like dd if=/dev/zero of=testfile bs=8m count=1000 seem to support > what dmesg reports by returning 96 Meg/sec transfer rates > FreeBSD limits individual I/O segments through the CAM subsystem to 64K. It can safely be raised to 128K via some patches that I have, and you will see a corresponding improvement in performance. I don't believe that it can be safely raised above that for the TWA controllers. Scott
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