Date: Sun, 8 Sep 2002 17:27:46 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: "Jack L. Stone" <jackstone@sage-one.net> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: dumpdev Message-ID: <20020908162746.GA6669@happy-idiot-talk.infracaninophi> In-Reply-To: <3.0.5.32.20020908105055.00fbeac8@mail.sage-one.net> References: <3.0.5.32.20020908105055.00fbeac8@mail.sage-one.net>
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On Sun, Sep 08, 2002 at 10:50:55AM -0500, Jack L. Stone wrote:
> Running 4.5-RELEASE
>
> I've got a server that crashes on a weekly basis and am trying to find out
> why.
>
> I noticed in the /etc/defaults/rc.conf file there is a setting for crash
> dumps:
> dumpdev="NO" # Device name to crashdump to (or NO)
> dumpdir="/var/crash" # Directory where crash dumps are to be stored
>
> But, I'm not sure what the "dumpdev" is supposed to be....
> Any tips appreciated for what may be a real dumb question....
Dumpdev is usually the same as your swap device, so /dev/ad0s1b or
/dev/da0s1b would be common choices. You need to have a swap area
that's at least slightly larger than the amount of RAM in your machine
for that to succeed. As the system is panicing, it doesn't have time
for such niceties as files, so the memory image just gets scribbled
over the end of the specified device.
Therefore, when you reboot after a crash, fairly early on, the
savecore(8) process is used to copy the crash image out of the dumpdev
into some files under the dumpdir for later consideration. That means
you need plenty of space in your dumpdir too.
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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