From owner-freebsd-scsi Wed Nov 1 20:58: 3 2000 Delivered-To: freebsd-scsi@freebsd.org Received: from aslan.scsiguy.com (aslan.scsiguy.com [63.229.232.106]) by hub.freebsd.org (Postfix) with ESMTP id 4C54E37B479 for ; Wed, 1 Nov 2000 20:58:01 -0800 (PST) Received: from aslan (localhost [127.0.0.1]) by aslan.scsiguy.com (8.11.0/8.9.3) with ESMTP id eA24vea67590; Wed, 1 Nov 2000 21:57:41 -0700 (MST) (envelope-from gibbs@aslan.scsiguy.com) Message-Id: <200011020457.eA24vea67590@aslan.scsiguy.com> To: The Hermit Hacker Cc: Tom Samplonius , freebsd-scsi@FreeBSD.ORG Subject: Re: iostat: tps for SCSI drives ... In-Reply-To: Your message of "Wed, 01 Nov 2000 18:43:55 -0400." Date: Wed, 01 Nov 2000 21:57:40 -0700 From: "Justin T. Gibbs" Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org >> Maxtags is the limit imposed by the quirk entry matching the device. > >Okay, under what conditions would dev_openings == maxtags? My best drive >that I can find on my various machines is a brand new LVD drive: You will only see this very early in the boot process before a device indicates that it cannot handle "maxtags" via a queue full or if you have a device that can really achieve "maxtags". For instance, some RAID arrays can perform the full 256 tags that can be outstanding is SCSI-2, but most drives max out at 64 or 63 tags. Only recently have I found some IBM drives that will support 128 tags. That said, the system will only allocate resources to support the number of transactions it is determined a device can use. The "maxtags" value is just an upper bound. -- Justin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message