[4881] in linux-scsi channel archive
Re: dual-attached disk
daemon@ATHENA.MIT.EDU (Mr. James W. Laferriere)
Wed Oct 14 05:57:16 1998
Date: Tue, 13 Oct 1998 21:29:44 -0700 (PDT)
From: "Mr. James W. Laferriere" <babydr@baby-dragons.com>
To: thoth@purplefrog.com
cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <199810131938.PAA24447@cairo.purplefrog.com>
Hello All,
I know for certain the there are several dual-host disk array's
available (DEC, now Compaq made/makes one.), Several are
raid arrays & now days are scsi based only . Just do a web search
on 'Dual-host disk arrays' or even 'Multi-host disk arrays' .
On Tue, 13 Oct 1998 thoth@purplefrog.com wrote:
> Dan Stromberg <strombrg@nis.acs.uci.edu> ,in message <3623A589.7EF4@nis.acs.uci
> .edu>, wrote:
>
> > In the sun world, you don't "just" connect the cable - it requires extra
> > software. Otherwise the buffer caches would get out of synch with what's
> > on the disk and really mess things up.
>
> I have never heard of anyone attempting simultaneous access to the disks. I
> wouldn't be surprised if it were done in a research situation, but the
> arbitration would be a pain in the ass, code-wise.
>
> > Now I suppose if you can only have one system access the disk at a time
> > - say the second only uses the disk if the first has certifiably
> > crashed, then that might be another matter.
>
> This is the standard model. One machine "locks" the disks, and the other
> machine takes them over when it is sure the other is a corpse (or when ordered
> to by the system operator, which is hopefully the normal case).
>
> There are Sparcs operating in this configuration under software from Veritas
> (and other vendors) in corporate machine rooms all over the country. Heck,
> there's one in my roommate's spare bedroom.
>
> As I understand it, the trick is to have the SCSI drivers on both ends "play
> nice" and not battle for control of the bus. I saw this on a wish list for
> the Linux kernel under the "clustering" heading. I wondered if anyone had
> made any progress on it.
>
> --
> Bob Forsman thoth@gainesville.fl.us
> http://www.gainesville.fl.us/~thoth/
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
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>
, JimL
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