From owner-freebsd-scsi Mon Dec 13 2: 4:36 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from fuchs.omnilink.de (hase.omnilink.de [194.64.25.65]) by hub.freebsd.org (Postfix) with ESMTP id 069B4150A2; Mon, 13 Dec 1999 02:04:32 -0800 (PST) (envelope-from ob@omnilink.net) Received: by fuchs.omnilink.de; id LAA05553; Mon, 13 Dec 1999 11:02:25 +0100 (MET) Received: from sondermuell.omnilink.de(194.64.25.218) by fuchs.omnilink.de via smap (V4.2) id xma005547; Mon, 13 Dec 99 11:02:18 +0100 Message-ID: <000c01bf4551$d8862240$da1940c2@omnilink.de> Reply-To: "Oliver Blasnik" From: "Oliver Blasnik" To: , "Mike Smith" References: <199912130832.AAA06120@mass.cdrom.com> Subject: Re: Again: CRD-Raid-Controller and FreeBSD 3.x Date: Mon, 13 Dec 1999 11:07:21 +0100 Organization: Omnilink ISC MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2314.1300 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2314.1300 Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Mike Smith wrote: > No. FreeBSD starts assuming that a drive will handle 64 tags, but it=20 > expects that the drive will correctly report a queue-full condition so = > that it can dynamically adjust this number downwards. And this could not work as far these maximum of 32 commands is = host-based, not lun-based. =20 > If the problem in this case is that the CMD unit is accepting a tagged = > command and then simply throwing it away, that's a bug in the CMD=20 > firmware. Correct. =20 > This may solve the "problem", but it will substantially degrade=20 > performance in the case where there's only one array on the = controller. Right. But on the other hand enables tq without bothering on = system-crashed :) Better slow than not running. =20 > > You might want to consider using a PCI:SCSI RAID controller like a = Mylex=20 > DAC960 or AMI MegaRAID. The host:cache bandwidth is _much_ better on=20 > these units, and they typically offer all of the features of the = external=20 > units at a lower price. > *g* Not a possibility for me. It has to be external for different reasons. We do not only have = FreeBSD, there's also Solaris and WinNT. Connecting an external system = enables transparency. Some CRD's are connected to two machines, = sometimes to share the array, sometimes to enable high-availability for = a system (hot-take-over of the drives). You could set up two CRD's to = the same drive bay to enable renundancy and cut off this single point of = failure. Last but not least, if one machine burns down, just take a new = hardware, plug it onto the raid and switch it on - running and up again. = Tell me how to do that with your controllers :) Cu, Oliver PS: I made a mistake on my cam_xpt.c-entry. the "min-tags" has to be >0 = to enable tq :) --=20 __ OMNILINK Internet Service Center GmbH / \ Hahnstrasse 70, 60528 Frankfurt __\ /_________ Tel.: (0 69)66 44 10 Fax: (0 69)66 44 11 99 O M N I L I N K http://www.omnilink.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message