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From: "Andrew V. Stesin" <stesin@elvisti.kiev.ua>
Message-Id: <199602011812.UAA07298@office.elvisti.kiev.ua>
Subject: Re: Am I root?! or How to mirror an 'a' partition?
To: rgrimes@GndRsh.aac.dev.com (Rodney W. Grimes)
Date: Thu, 1 Feb 1996 20:12:21 +0200 (EET)
Cc: stesin@elvisti.kiev.ua, hackers@FreeBSD.org, ccd@forgery.CS.Berkeley.EDU
In-Reply-To: <199602011624.IAA20540@GndRsh.aac.dev.com> from "Rodney W. Grimes" at Feb 1, 96 08:24:32 am
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Hello,

[...]
# Because the first 16 blocks of the a partition are special, they
# contain the bootblocks and disklabel.  These are protected from
# writes and require a special ioctl to be able to write them.
# > 
# > 	dd if=/dev/rsd0a of=/dev/rsd1a bs=16b skip=1
# 
# Try adding a seek=1 so you skip over the first 16b of the output
# device too.  Skip only effects the input file.
 
	Oh, God. Shame on me. I apologize for the dumb question.
	Probably beer made me blind while doing RTFM on dd (1). )-;

	sd (4) doesn't clearly state that first 16b are R/O even
	if the disk is _not_ mounted at all, BTW.
	One need to read IOCTLS section carefully to figure the idea.
	Can this fact be added to the sd (4) manpage?

	Thanks a lot for the solution!

# -- 
# Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
# Accurate Automation Company                 Reliable computers for FreeBSD
# 


-- 

	With best regards -- Andrew Stesin.

	+380 (44) 2760188	+380 (44) 2713457	+380 (44) 2713560

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