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Date: Tue, 16 Jan 2007 13:51:57 -0500
From: Kris Kennaway <kris@obsecurity.org>
To: Doug Ambrisko <ambrisko@ambrisko.com>
Message-ID: <20070116185157.GB97568@xor.obsecurity.org>
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Cc: Scott Oertel <freebsd@scottevil.com>, Willem Jan Withagen <wjw@digiware.nl>,
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Subject: Re: running mksnap_ffs
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On Tue, Jan 16, 2007 at 10:13:57AM -0800, Doug Ambrisko wrote:

> FWIW, with this patch I find making snap-shots a lot more reliable:
>=20
> --- sys/ufs/ffs/ffs_snapshot.c.orig	Wed Mar 22 09:42:31 2006
> +++ sys/ufs/ffs/ffs_snapshot.c	Mon Nov 20 14:59:13 2006
> @@ -282,6 +282,8 @@ restart:
>  		if (error)
>  			goto out;
>  		bawrite(nbp);
> +		if (cg % 10 =3D=3D 0)
> +			ffs_syncvnode(vp, MNT_WAIT);
>  	}
>  	/*
>  	 * Copy all the cylinder group maps. Although the
> @@ -303,6 +305,8 @@ restart:
>  			goto out;
>  		error =3D cgaccount(cg, vp, nbp, 1);
>  		bawrite(nbp);
> +		if (cg % 10 =3D=3D 0)
> +			ffs_syncvnode(vp, MNT_WAIT);
>  		if (error)
>  			goto out;
>  	}
>=20
> or things can get wedged.  We have some other patches as well that might
> be required.  As a hack on a local server we have been using snap shots
> to do a "hot" back-up of a data base each morning.  This is based on
> 6.x.

What do you mean by "get wedged"?  Are you seeing a deadlock, and if
so then what are the details?  When you say 6.x, do you mean
up-to-date RELENG_6?  There were various snapshot deadlock fixes
committed over the past year including some in the past few months.

Kris

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