From owner-freebsd-stable@FreeBSD.ORG  Fri Nov 18 23:13:39 2005
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Date: Fri, 18 Nov 2005 18:13:51 -0500
From: Parv <parv@pair.com>
To: Michal Mertl <mime@traveller.cz>
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Cc: delphij@delphij.net, Johan =?iso-8859-1?Q?Str=F6m?= <johan@stromnet.org>,
	pjd@freebsd.org, freebsd-stable@freebsd.org
Subject: Re: Page fault, GEOM problem??
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in message <1132353600.903.19.camel@genius1.i.cz>, wrote Michal
Mertl thusly...
>
> Johan Ström wrote:
> > 
> > On 18 nov 2005, at 18.43, Xin LI wrote:
...
> > So, it seems it does run savecore after running dumpon and
> > mounting  disks etc... Is that wrong?
> 
> No, this is normal. When you run savecore you need to have mounted
> filesystems. In order to mount the filesystems they may have to be
> checked. The fsck program requires big amount of memory to check
> larger filesystems so the swap has to be enabled. Core dumps are
> written to the dump device (swap) from the end whereas the swap is
> normally used from the beginning (or the other way around).
> Therefore there's quite a big chance that, even when the swap has
> to be used for fsck, the core dump is intact and usable.

Is there any formula to calculate the size of swap to account for
fsck & core dump while assigning swap size (short of having two swap
partitions)?


> If the usage of the swap file by fsck corrupts the core dump you
> may start after next crash in single user mode and run the
> commands manually (without enabling swap).

Is that after kernel (re)boots?  And would the commands to be
executed be savecore followed by swapon?


  - Parv

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