From owner-freebsd-net@FreeBSD.ORG Mon Sep 26 19:29:43 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1E342106564A; Mon, 26 Sep 2011 19:29:43 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout026.mac.com (asmtpout026.mac.com [17.148.16.101]) by mx1.freebsd.org (Postfix) with ESMTP id 049588FC08; Mon, 26 Sep 2011 19:29:42 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; CHARSET=US-ASCII Received: from cswiger1.apple.com ([17.209.4.71]) by asmtp026.mac.com (Oracle Communications Messaging Server 7u4-23.01 (7.0.4.23.0) 64bit (built Aug 10 2011)) with ESMTPSA id <0LS5002GI7CU9Z00@asmtp026.mac.com>; Mon, 26 Sep 2011 11:29:19 -0700 (PDT) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.4.6813,1.0.211,0.0.0000 definitions=2011-09-26_07:2011-09-26, 2011-09-26, 1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 ipscore=0 suspectscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=6.0.2-1012030000 definitions=main-1109260206 From: Chuck Swiger In-reply-to: Date: Mon, 26 Sep 2011 11:29:17 -0700 Message-id: <69A27071-39FF-4AFA-8E06-05ECA1E8DD2C@mac.com> References: <1317017255.2706.5.camel@jshupe-2530p.osre.org> To: Martin Wilke , James Shupe X-Mailer: Apple Mail (2.1084) Cc: freebsd-net Net Subject: Re: Data centers failure proof with CARP. X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Sep 2011 19:29:43 -0000 Hi-- On Sep 26, 2011, at 9:53 AM, Martin Wilke wrote: > Any other Idea what we can do to get a failover between both servers? Multi datacenter failover is *hard*. You have to evaluate which parts are static systems-- ie, display the same web images from all DCs, provide a current UTC timestamp from NTP, or whatever-- and which parts are transactional: ie, people's email, or placing orders on an online store, etc. Failover of static systems is relatively easier, as they don't need to change from one DC to another, and you can just use short DNS TTLs or outsource to a content distribution network like the various CDN / cloud providers (Akamai, Amazon, Level3, Azure, whatever). Failover of the transactional portion requires extensive effort to understand the transactional model-- are you active/standby, with write-through to the primary and cacheable read-back elsewhere, with a planned transition in the event of failure of the active to promote a standby to active; or are multiple DCs active with some form of load-balancing in place to distribute transactions (geolocation by client IP towards closer DCs, perhaps), etc. And you also have to consider what happens after a failure, and how you reintegrate DCs once a failure is resolved and reassemble your transactional data to be coherent. Regards, -- -Chuck