From owner-freebsd-cluster@FreeBSD.ORG  Sat Sep 24 16:06:58 2005
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Date: Sat, 24 Sep 2005 18:06:56 +0200 (CEST)
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From: Oliver Fromme <olli@lurza.secnetix.de>
To: freebsd-cluster@FreeBSD.ORG
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Subject: Re: Options for synchronising filesystems
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Just a few things that came to my mind when reading your
message ...

Brian Candler <B.Candler@pobox.com> wrote:
 > [...]
 > 2. Run the images directly off NFS
 > ----------------------------------
 > [...]
 > As far as I know, NFS clients don't support the idea of failing over from
 > one server to another, so I'd have to make a server pair which transparently
 > fails over.

NetApp filers support that (in cluster configuration).  It
works very well, I've used such NetApp filer clusters as
NFS servers for a server farm running FreeBSD for several
years.

Disadvantage:  Not exactly cheap.

 > 6. Journaling filesystem replication
 > ------------------------------------
 > 
 > If the data were stored on a journaling filesystem on the master box, and
 > the journal logs were distributed out to the slaves, then they would all
 > have identical filesystem copies and only a minimal amount of data would
 > need to be pushed out to each machine on each change. (This would be rather
 > like NetApps and their snap-mirroring system). However I'm not aware of any
 > journaling filesystem for FreeBSD, let alone whether it would support
 > filesystem replication in this way.

DragonFly BSD supports exactly that.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

We're sysadmins.  To us, data is a protocol-overhead.