Date: Mon, 1 Sep 2003 23:51:17 -0700 (PDT) From: Doug Barton <DougB@FreeBSD.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: freebsd-current@freebsd.org Subject: Re: swapon vs savecore dilemma Message-ID: <20030901233731.U6074@znfgre.qbhto.arg> In-Reply-To: <41076.1062480964@critter.freebsd.dk> References: <41076.1062480964@critter.freebsd.dk>
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On Tue, 2 Sep 2003, Poul-Henning Kamp wrote:
> Hmm, that was an unfortunate side effect.
Heh, well, stuff happens. I think your idea of opening swap exclusive is
probably a good one, but it will require some gymnastics to accomodate
it. One thing that'd really help is an option to savecore that tells us
if there is a dump to deal with or not. If I had that, we could do
something like this in /etc/rc.d/savecore
if there is no dump
exit
else
does fsck -p of the fs to write the dump to succeed?
mount it rw
write the dump
clear the dump
exit
else
does try fsck -y of the fs without swap succeed?
mount, write, clear, exit
else
???
At the ??? point I'm not sure how best to proceed, since if we swapon to
the same partition with the dump, it's likely to corrupt the dump, yes?
On the other hand, we're doing swapon before savecore now, so I guess
I'm curious about how dangerous this really is.
Probably the right thing to do is to swapon, fsck -y, and if it succeeds
then swapoff, and try writing the dump anyway. I just want to be
sure before we start re-writing rc.d/savecore.
So, the first question is does the pseudocode above look reasonable, and
the second question is what's the likelihood of getting an option to
savecore to detect a dump to play with?
Doug
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