From owner-freebsd-current Tue Dec 21 12: 4: 9 1999 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 16C46154E2 for ; Tue, 21 Dec 1999 12:04:07 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id MAA80595; Tue, 21 Dec 1999 12:04:00 -0800 (PST) (envelope-from dillon) Date: Tue, 21 Dec 1999 12:04:00 -0800 (PST) From: Matthew Dillon Message-Id: <199912212004.MAA80595@apollo.backplane.com> To: Peter Jeremy Cc: Greg Lehey , FreeBSD current users Subject: Re: Recent current hangs frequently for 1 to 2 seconds. References: <19991219143759.C465@freebie.lemis.com> <199912190416.UAA01125@apollo.backplane.com> <19991221095213.L440@freebie.lemis.com> <199912210019.QAA62510@apollo.backplane.com> <19991221110148.N440@freebie.lemis.com> <199912210108.RAA62736@apollo.backplane.com> <99Dec21.123129est.40326@border.alcanet.com.au> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG : :On 1999-Dec-21 12:08:27 +1100, Matthew Dillon wrote: :> Tape drives may: :> * Not support disconnection ... :> * Implement a crappy SCSI command stack ... :> * Not properly terminate the SCSI bus ... :> * Introduce too much noise onto the SCSI bus due to bad design. : :Do modern drives still support these various `features'? I know :there used to be problems, but I thought Greg was using a (presumably :fairly recent) DLT drive. Given the normal data rates associated with :DLT drives, I would have thought they would behave fairly well. : :BTW, since Greg mentioned he was thinking of using an AHA-1542B - :I've found that mine won't work in sync mode. Whenever I tried to :read or write, it would just timeout, until I disabled SYNC. (And :if I increased the sync speed beyond 5MHz, the kernel would usually :panic). : :Peter They are supposed to support disconnection, and most do. But tape drives tend to have buggy firmware - for example, the 20G Exabyte drives can crash a SCSI bus if you use too small a block size. It just isn't worth mixing them with your disks. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message