From owner-freebsd-stable Mon Jul 3 1:37:48 2000 Delivered-To: freebsd-stable@freebsd.org Received: from org.chem.msu.su (org.chem.msu.su [158.250.32.94]) by hub.freebsd.org (Postfix) with ESMTP id 5DBC637B80A for ; Mon, 3 Jul 2000 01:37:18 -0700 (PDT) (envelope-from kostik@org.chem.msu.su) Received: from org.chem.msu.su. (org.chem.msu.su. [158.250.32.94]) by org.chem.msu.su (8.9.3/8.9.3) with ESMTP id MAA39609; Mon, 3 Jul 2000 12:36:02 +0400 (MSD) Date: Mon, 3 Jul 2000 12:36:02 +0400 (MSD) From: kostik To: Kent Stewart Cc: David Gilbert , freebsd-stable@freebsd.org Subject: Re: Dump takes ages on SCSI. (several times faster on IDE) In-Reply-To: <395FF18D.6B47A620@3-cities.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sun, 2 Jul 2000, Kent Stewart wrote: > > >>>>> "Kent" == Kent Stewart writes: > > > > >> I then noticed that the IDE would crashdump somewhere around 10 > > >> times faster than the SCSI disk. > > >> > > >> Why? Can the SCSI speed be improved? > > > > Kent> It depends on what 2940 and what IDE drive you are talking > > Kent> about. I have a Maxtor UDMA66 that is 20MB/s faster in some > > > > I don't think this explains it at all. It would appear that the SCSI > > driver is running in some "extra safe" mode, or something. It has > > 512M to write sequentually to a partition... and the counting on the > > screen, we're looking at 2 to 3 seconds-per-megabyte (on a drive that > > delivers write performance of about 10M/s in normal operation). > > > > Maybe what I should have said that the ratio of regular operation to > > dump performance of the ide driver is about 1:1 while it's 10:1 for > > the SCSI driver... why is this? > > I don't have any idea up front. One thing comes to mind and that is > does your Quantum come up with "tagged queuing enabled". My IBM has i have the same hdd, ibm dcas-34330W. it is very interesting that "tagged queuing" was enabled for scsi driver while i was working with freebsd-3.0-release and became disabled (or isn't recognised) when i upgrade to freebsd-4.0-release. > that disabled or more precisely never enabled, which makes it slower > and safer. My dmesg shows the drive as > > da0: Fixed Direct Access SCSI-2 device > da0: 40.000MB/s transfers (20.000MHz, offset 8, 16bit) > da0: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C) > can you explain me this "safeness" please ? WBR, Konstantin Yu. Pasichnichenko E-mail : kostik@org.chem.msu.su FIDO : 2:5020/118.82@fidonet.org p.s. sorry my bad english. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message