From owner-freebsd-hardware Mon Oct 14 15:44:34 1996 Return-Path: owner-hardware Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id PAA02384 for hardware-outgoing; Mon, 14 Oct 1996 15:44:34 -0700 (PDT) Received: from GndRsh.aac.dev.com (GndRsh.aac.dev.com [198.145.92.241]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id PAA02377 for ; Mon, 14 Oct 1996 15:44:30 -0700 (PDT) Received: (from rgrimes@localhost) by GndRsh.aac.dev.com (8.7.5/8.7.3) id PAA14956; Mon, 14 Oct 1996 15:44:10 -0700 (PDT) From: "Rodney W. Grimes" Message-Id: <199610142244.PAA14956@GndRsh.aac.dev.com> Subject: Re: sticky drives (was: your mail) In-Reply-To: from Dave Babler at "Oct 14, 96 03:34:48 pm" To: dbabler@Rigel.orionsys.com (Dave Babler) Date: Mon, 14 Oct 1996 15:44:10 -0700 (PDT) Cc: freebsd-hardware@freebsd.org X-Mailer: ELM [version 2.4ME+ PL25 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hardware@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > > > On Mon, 14 Oct 1996, Rodney W. Grimes wrote: > > > > This is extremely dangerous, BTW. When you take the drive out of the > > > freezer, condensation may form on the platters as the drive heats up. > > > Conversely, frost may form on the platters as the drive drops below freezing. > > > > This is absolutely true, dropping a drive below 0 deg C is a sure fire > > way to damage it. Even the non-operating temp spec on almost all mfg's > > disk is +5 C on the lower end. Having done MIL-SPEC drive work that > > had to operate over -55 to +125 C the actual hardest part of this range > > was the -5 to +5 C range, condensation being a real killer. > > Isn't the chamber where the platters reside hermetically sealed? If so, > how would moisture be there to condense in the first place? They are not hermetically sealed, they have a bidirection presure release and filter valve. Look very closely at your disk drives. If they did not do this (and the tried) the cases would blow apart when ship via unpressearized air freight at someplace close to 22K feet MSL. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation, Inc. Reliable computers for FreeBSD