Date: Tue, 15 Oct 1996 17:16:32 +0500 From: "David Alderman" <dave@persprog.com> To: Dave Babler <dbabler@Rigel.orionsys.com>, freebsd-hardware@FreeBSD.org Subject: Re: sticky drives (was: your mail) Message-ID: <76F66B727B@dasa.ppi.com>
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> From: Dave Babler <dbabler@Rigel.orionsys.com> > > > On Mon, 14 Oct 1996, Rodney W. Grimes wrote: > > > 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. > > > > > > > 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. > > > > Given the normally controlled environment drives are supposed to operate > in, that makes economic sense. I am surprised that an overpressure of > 10-12 psi would rupture the case, though, on a volume that small, but then > gain the castings that I've seen recently are quite thin to save material. > > -Dave I would think it was the seals and not the case that would rupture. Then you would have a permanent "blow hole" somewhere on the drive. Seagate once had the wisdom to place one of the drive seals on the side of the drive adjacent to the mounting brackets. If the frame the drive was mounted in was too tight the seal would peal away exposing the drive to open air. I discovered this in a friend's computer because I heard a middle C "whistle" which was the air flow inside the drive blowing over the resultant hole! This may not be relevant - but it's not a bad story ;-) ====================================== When philosophy conflicts with reality, choose reality. Dave Alderman -- dave@persprog.com ======================================
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