From owner-freebsd-hackers Thu Mar 5 12:12:52 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id MAA12537 for freebsd-hackers-outgoing; Thu, 5 Mar 1998 12:12:52 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from sendero.simon-shapiro.org (sendero-fxp0.Simon-Shapiro.ORG [206.190.148.34]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id MAA12475 for ; Thu, 5 Mar 1998 12:12:35 -0800 (PST) (envelope-from shimon@sendero-fxp0.simon-shapiro.org) Received: (qmail 772 invoked by uid 1000); 5 Mar 1998 20:18:41 -0000 Message-ID: X-Mailer: XFMail 1.3-alpha-021598 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: Date: Thu, 05 Mar 1998 12:18:41 -0800 (PST) Reply-To: shimon@simon-shapiro.org Organization: The Simon Shapiro Foundation From: Simon Shapiro To: Remy NONNENMACHER Subject: RE: SCSI Bus redundancy... Cc: karl@mcs.net, grog@lemis.com, hackers@FreeBSD.ORG, blkirk@float.eli.net, jdn@acp.qiv.com, tlambert@primenet.com, wilko@yedi.iaf.nl, sbabkin@dcn.att.com Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 05-Mar-98 Remy NONNENMACHER wrote: ... > And what about sending all packets to two RDBMS at the same time and > dropping one of the results when it come back?. Instead of having only a > copy, you can also have fault tolerancy since if one machine goes down, > you simply send the result from the other ? (Would probably need clock > synchonisation and on random numbers that can be generated by either > machine and a physical DB copy before starting). Surely their is a lot of > applications that can be forked/merged like this from a network point of > vue. (I remember seeing something about equaly MACed NICS with one > machine > listening the result of the other and the two machine running the same > program (using a lightly synchronised kernel)). That will work too. The idea is to move as much of the redundency to lower and lower layers and make the application as oblivious to these things as possible. Somethines you do that in the name of simplicity, sometimes in the name of sanity; As was mentioned here before, an application cannot differentiate between a slow server and a dead one (not for a while anyway). A computer, with a simple device in it can detect crashing very reliably and very quickly. ---------- Sincerely Yours, Simon Shapiro Shimon@Simon-Shapiro.ORG Voice: 503.799.2313 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message