*BSD News Article 22861


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Newsgroups: comp.os.386bsd.bugs
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From: todd@flex.eng.mcmaster.ca (Todd Pfaff)
Subject: Re: more problems with 2nd IDE drive
Message-ID: <1993Oct26.175939.7882@mcshub.dcss.mcmaster.ca>
Sender: usenet@mcshub.dcss.mcmaster.ca
Nntp-Posting-Host: flex1.eng.mcmaster.ca
Reply-To: todd@flex.eng.mcmaster.ca
Organization: McMaster University
Date: Tue, 26 Oct 1993 17:59:39 GMT
Lines: 49

In article <1993Oct25.162355.28536@mcshub.dcss.mcmaster.ca>, I wrote:

> I'm also having a problem with a 2nd IDE drive under 386BSD-0.1+pk0.2.4.  If I try
> to use an additional swap partition on the 2nd drive, my disk label eventually gets
> corrupted.  Fortunately, I had saved a backup disk label on the other drive and I
> could boot and restore the corrupt label so nothing is lost.  Other than that, the
> 2nd IDE drive works flawlessly.  I've checked my disklabel to ensure that the swap
> partition is not overlapping anything.

The problem was that my swap partition (wd1b) started at cylinder 0 of the 386BSD
partition space.  I also had a UFS partition (wd1a) but for some reason I started
it after the swap partition.  Apparently, the UFS code knows that the disklabel,
is placed at cylinder 0 of the 386BSD partition space and so avoids stomping on it,
but the swap code is not so intelligent.  Is this correct?  If so, the moral of the
story is: do not create a disklabel with a swap partition starting at cylinder 0.
How many sectors do you have to reserve for the system (boot code, disklabel, etc)?
Is it best to just leave an entire cylinder?

I changed my disklabel to start at cylinder 1 and all seems fine now.

Thanks for the responses!

> From: osyjm@pdq.coe.montana.edu (Jaye Mathisen)
> 
> I suspect your disklabel on the second drive is bogus.

> From: Dan Yergeau <yergeau@leland.stanford.edu>
> 
> Does your swap partition start on the same cylinder that either
> partition c or d starts on?  If so, then this is probably the cause.
> If I recall correctly, the disklabel is stored in the first sector of
> the c partition.
> 
> When posting a disklabel problem, it is best to include the disklabel.

> From: L Jonas Olsson <ljo@murphy.eeap.cwru.edu>
> 
> Do you have the b partition start at cylinder zero? Or are you swapping
> to partion a? The disklabel is on cylinder zero, and partition a knows
> not to overwrite it (at least if you have ufs on partion a).
> I have had two IDE drives and swapped to both, never had any troubles.

---
Todd Pfaff                       \  Internet: todd@flex.eng.mcmaster.ca
Dept. of Mechanical Engineering   \    Voice: (905) 525-9140 x22902
McMaster University                \     FAX: (905) 572-7944
Hamilton, Ontario, CANADA  L8S 4L7  \