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To: Warren Block <wblock@wonkity.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Fri, 07 Oct 2011 14:27:05 CST."
	<alpine.BSF.2.00.1110071352210.2450@wonkity.com>
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Date: Fri, 07 Oct 2011 21:10:54 +0000
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Cc: Garrett Cooper <yanegomi@gmail.com>, Glen Barber <gjb@FreeBSD.org>,
	freebsd-current@FreeBSD.org, Benjamin Kaduk <kaduk@mit.edu>,
	Arnaud Lacombe <lacombar@gmail.com>
Subject: Re: aliasing (or renaming) kern.geom.debugflags
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In message <alpine.BSF.2.00.1110071352210.2450@wonkity.com>, Warren Block write
s:

># mount /dev/da0p2 /mnt
># dd if=/tmp/FreeBSD-9.0-BETA3-amd64-memstick.img of=/dev/da0 bs=64k
>dd: /dev/da0: Operation not permitted
># sysctl kern.geom.debugflags=16
>kern.geom.debugflags: 0 -> 16
># dd if=/tmp/FreeBSD-9.0-BETA3-amd64-memstick.img of=/dev/da0 bs=64k
>10463+1 records in
>10463+1 records out
>685731840 bytes transferred in 52.915362 secs (12959031 bytes/sec)
>
>Followed by removing the memory stick without unmounting it to avoid 
>overwriting part of the image.  No obvious problems, but no, it's not 
>polite.  (I'm thinking "automounter" here.)

And you are sure the stick now contains what you expect ?

If the dirty filesystem had blocks to write, it might have done so...

debugflags are called debugflags for a reason:  You should never
need them, unless you are debugging a problem.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.