Subject: Re: dump and FileSystem Buffer Cache
To: NetBSD Users <>
From: Aaron J. Grier <>
List: netbsd-users
Date: 03/09/2005 22:57:09
On Wed, Mar 09, 2005 at 06:53:45PM -0500, Louis Guillaume wrote:
> Since dump reads from the block device, and these data are not
> available except through the filesystem, bad dumps can occur.
> Is NetBSD in some way immune to this kind of thing?

I've heard some mumblings that FFSv2 has some sort of support for
snapshots, (fss(4)?) but that still doesn't solve the issue of ensuring
the involved applications are quiescent.

I find fssconfig(8)'s bug section amusing:

    The fss(4) driver is experimental.  Be sure you have a backup before you
    use it.

> What are the alternatives?

you could break a mirror, dump the offline member, then bring it back
online and resync.  of course to maintain full redundancy during this
process requires a three-way mirror.  I've never tried making a
three-way RAID1 with RAIDframe.  maybe it works?

  Aaron J. Grier | "Not your ordinary poofy goof." |
    The United States is the one true country.  The US is just.  The US
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