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Topic: Failover

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	Failover and Replication in a Cluster
		This section describes the connection and failover processes for requests that are proxied to clustered servlets and JSPs.
		After a failover, WebLogic Server chooses a new secondary server to replicate EJB session states (if another server is available in the cluster).
		Failover for entity beans and EJB handles requires that the cluster address be specified as a DNS name that maps to all server instances in the cluster and only server instances in the cluster.
	edocs.bea.com /wls/docs81/cluster/failover.html (5614 words)

	Failover - Wikipedia, the free encyclopedia
		Failover is the capability to switch over automatically to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network.
		Failover happens without human intervention and generally without warning, unlike switchover.
		Systems designers usually provide failover capability in servers, systems or networks requiring continuous availability and a high degree of reliability.
	en.wikipedia.org /wiki/Failover (89 words)

	[No title]
		In many (if not most) cases, the failover protocol is symmetric with respect to the primary or secondary nature of the servers, and so it is often appropriate to discuss "updating the partner server", since it could be a primary server updating a secondary server or a secondary server updating a primary server.
		When a connection is received from the partner, the unique failover endpoint to which the message is directed is determined solely by the IP address of the partner, the relationship-name, and the role of the receiving server.
		In a failover context, both servers need to be configured with the proper reservations in an identical manner, but if we stop there problems can occur around the edge conditions where reservations are made for an IP address that has already been leased to a different client.
	www.ietf.org /proceedings/04mar/I-D/draft-ietf-dhc-failover-12.txt (14829 words)

	Failover 0.5.20 Home Page
		This package of failover utilites is designed to solve this problem in some cases.
		The daemon is polled at regular intervals in time by a failover shell, which then decides whether a service needs to be started on the local machine or not.
		Failover is award winning software: it has won the first prize in the first Swiss Open Source Competition.
	failover.othello.ch (628 words)

	SQL Server 2005 Part 3 - High Availability and Scalability Enhancements - Failover Clustering (Site not responding. Last check: 2007-09-15)
		Failover clustering has been supported since SQL Server 7.0 so it is not surprising that its latest implementation is a combination of already familiar (and stable) technology with a number of useful improvements.
		These factors, combined with the failover strategy, affect the number of cluster nodes and their configuration (it is possible to designate specific nodes as potential or preferred owners of particular resource groups, while prohibiting others from participating in their failover).
		While the goal of database mirroring and failover clustering is to provide high availability through automatic failover without data loss, their characteristics (and, consequently, the manner in which they accomplish this goal) are very different.
	www.databasejournal.com /features/mssql/article.php/3444181 (1984 words)

	Cisco PIX: Failover Demystified (Site not responding. Last check: 2007-09-15)
		The role of Primary or Secondary PIX is established by the Failover cable.
		Failover —When the active PIX Firewall fails and the standby PIX Firewall becomes active, all connections are lost and client applications must initiate a new connection to restart communication through the PIX Firewall.
		Stateful failover —When the active PIX Firewall fails and the standby PIX Firewall becomes active, the same connection information is available at the new active PIX Firewall, and end-user applications are not required to do a reconnect to keep the same communication session.
	www.informit.com /articles/article.asp?p=24686 (2919 words)

	Using Failover
		Failover is compatible with both routed and transparent firewall modes, and with single and multiple context modes.
		To accommodate the failover communications between the FWSMs, we recommend that you configure a trunk port between the two switches that carries the failover and state VLANs.
		The main differences between the two modules in a failover pair are related to which module is active and which module is standby, namely which IP addresses to use and which module actively passes traffic.
	www.cisco.com /univercd/cc/td/doc/product/lan/cat6000/mod_icn/fwsm/fwsm_2_3/fwsm_cfg/failover.htm (5630 words)

	Cisco - How Failover Works on the Cisco Secure PIX Firewall
		The basic failover communication is through the failover cable or through the LAN interface which is configured with the failover lan interface interface_name command in PIX OS version 6.2 and later.
		Failover does not start to monitor the network interfaces until it has heard the second "hello" packet from the other unit on that interface.
		With failover enabled, do not boot the secondary unit without first booting the primary one, since the MAC address used is from the primary unit.
	www.cisco.com /warp/public/110/failover.html (5425 words)

	Failover/Failback Policies on Microsoft Cluster Server
		The failover threshold is the number of times the group can fail over within the number of hours specified by the failover period.
		For example, if a group failover threshold is set to 5, and its failover period set to 3, Cluster Server will failover the group at most five times within a three hour period.
		When you configure a group to automatically failback to the preferred node, you specify whether you want the group to failback as soon as the preferred node is available or to failback only during specific hours that you define.
	support.microsoft.com /?id=197047 (657 words)

	27. LVS: High Availability, Failover protection
		On simple failover, where a new director is just swapped in, in place of the old one, the session information is not transferred to the new director and the client will loose their session.
		Director failover occurs by transfering the VIP to the backup director, bringing down the primary director, and by using the backup copy of the connection table (put there by the synch demon) on the backup director.
		With dynamic routing then, after failover, the default route for the backup router is the default route of the active router, and not an IP on the active router.
	www.austintek.com /LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.failover.html (11711 words)

	Microsoft SQL Server 2000 Failover Clustering
		Failover clustering is a process in which the operating system and SQL Server 2000 work together to provide availability in the event of an application failure, hardware failure, or operating-system error.
		Failover clustering provides hardware redundancy through a configuration in which mission critical resources are transferred from a failing machine to an equally configured server automatically.
		Instead of configuring your failover cluster to allow the instances to fail first to a node with another instance of SQL Server 2000 running, the fourth node should be configured as the primary failover.
	www.microsoft.com /technet/prodtechnol/sql/2000/maintain/failclus.mspx (13965 words)

	MF Bliki: CatastrophicFailover (Site not responding. Last check: 2007-09-15)
		One of the oft advertised features of modern application servers is that they provide failover in a cluster.
		Failover can add even more reliability, if a server goes down in the middle of a interaction the cluster can move that interaction to another server.
		So when the failover kicks in, the deadly requests gets moved to another server which it can then bring down in turn.
	martinfowler.com /bliki/CatastrophicFailover.html (252 words)

	What is failover? - a definition from Whatis.com
		- Failover is a backup operational mode in which the functions of a system component (such as a processor, server, network, or database, for example) are assumed by secondary system components when the primary component becomes unavailable through either failure or scheduled down time.
		Failover can apply to any aspect of a system: within an personal computer, for example, failover might be a mechanism to protect against a failed processor; within a network, failover can apply to any network component or system of components, such as a connection path, storage device, or Web server.
		The capacity for automatic failover means that normal functions can be maintained despite the inevitable interruptions caused by problems with equipment.
	searchstorage.techtarget.com /sDefinition/0,,sid5_gci753437,00.html (429 words)

	Simple Failover - Features
		Simple Failover continuously monitors your servers and updates DNS accordingly, so that you domain name is always pointing to a functional server.
		Simple Failover can update DNS so that all functional servers for a domain name receives traffic on a rotating basis (utilizing DNS round robin), or it can update DNS so that only one server receives traffic (by server priority) if you have a primary server and one or more backup servers.
		The Simple Failover "Activity Log tab" shows what is currently happening, and how the program reacts to the monitoring process in real time.
	www.simplefailover.com /features.aspx (866 words)

	Network Appliance - FAS Series - Clustered Failover High-Availability Solution (Site not responding. Last check: 2007-09-15)
		NetApp Clustered Failover is installed on a pair of NetApp storage controllers, and during normal operation each controller services its own workload while monitoring the health of its "partner" controller.
		Clustered Failover administration tasks are simple, intuitive, and easy to use, minimizing management overhead and reducing operator error.
		End users are not impacted by a failover; clients continue to access data the same way after a failover.
	www.netapp.com /products/software/clustered.html (313 words)

	Catastrophic Failover \| PHP Everywhere
		Whatever the case, I think it would be a better idea to move this task off to the cluster managers (or whatever X vendor wants to call it/them) as they are allready monitoring the health of the machines in the farm anyways.
		Both solutions could be configured to behave (balance load, manage failover, etc) in the much the same way (eventhough how they are configured is different).
		The only thing that would then be required is that the vendors come in and create a mechanism for tracking transmissions (sticky sessions?) and their effects upon a given machine.
	phplens.com /phpeverywhere?q=node/view/176 (1553 words)

	What is failover? - A Word Definition From the Webopedia Computer Dictionary
		A backup operation that automatically switches to a standby database, server or network if the primary system fails or is temporarily shut down for servicing.
		Failover is an important fault tolerance function of mission-critical systems that rely on constant accessibility.
		Failover automatically and transparently to the user redirects requests from the failed or down system to the backup system that mimics the operations of the primary system.
	www.webopedia.com /TERM/F/failover.html (133 words)

	How to Perform Microsoft SQL Server Database Log Shipping
		The DBA must still manually failover the server, which means the DBA must be present when the failover occurs.
		When it comes time for the actual failover, you must do one of two things to make your applications work: either rename the standby server the same name as the failed production server (and the IP address), or re-point your user's applications to the new standby server.
		Another aspect of the failover process you will want to plan for is how you will make the move back from the standby server to the production server once the production server is working again.
	www.sql-server-performance.com /sql_server_log_shipping.asp (4867 words)

	Failover Clustering
		For example, during an operating system failure or a planned upgrade, you can configure one failover cluster to fail over to any other node in the failover cluster configuration.
		For information about upgrading to a SQL Server 2000 failover cluster, see Upgrading to a SQL Server 2000 Failover Cluster.
		Reinstall or rebuild a virtual server on any node in the failover cluster without affecting the other nodes.
	doc.ddart.net /mssql/sql2000/html/adminsql/ad_clustering_7t9v.htm (510 words)

	Failover Services (FOS)
		No additional systems or devices are required, and except for the temporary loss of the service(s) during failure, the failover process is transparent to end users.
		Failover will occur when the service becomes unresponsive to FOS monitoring; this is independent of the number of users actually using the service.
		This makes it easier to migrate existing environments where the IP services are already being provided by multiple servers, to having those services provided by a single "more fault-tolerant" cluster and keeping the changes transparent to end users.
	www.redhat.com /docs/manuals/haserver/RHHAS-1.0-Manual/ch-fos.html (799 words)

	Installation order for SQL Server 2000 Enterprise Edition on Microsoft Cluster Server
		To create a failover cluster, you must be a local administrator with rights to log on as a service and to act as part of the operating system on all computers in the failover cluster.
		If the failover node has less physical memory than the original node, instances of SQL Server may fail to start or may start with less memory than they had on the original node.
		The cluster disks to use for failover clustering should all be in a single cluster group and owned by the node from which the Setup program is run.
	support.microsoft.com /?kbid=243218 (3315 words)

	XOsoft's high availability data protection solution, WANSyncHA, for data replication and data recovery
		WANSyncHA offers automated push-button or fully automatic failover of mission-critical application servers over a LAN or WAN, application-aware status monitoring, integrated continuous data protection as a guard against data corruption, and completely non-disruptive automatic testing of your disaster recovery system, all in a system that sets the standard for ease of configuration and management.
		Be sure to view our library of recorded webcasts and demos pertaining to our automatic failover solution or contact us for information related to your specific business continuity needs.
		Failover may be triggered automatically, or WANSyncHA can be configured to alert the appropriate administrator who can trigger an automated failover with a simple push of a button.
	www.xosoft.com /products/f_WANSyncHA.shtml (2417 words)

	LR101 Linux VPN Router Project - Linux VPN + DSL + ISDN Failover Router :: FreeS/WAN :: L2TP/IPSec :: PPtP ::-::-:: ...
		This includes especially the internet/vpn failover and support of all major routing protocols, such as IP, BGP, OSPF or even GRE which will ensure operation in a cisco environment.
		A selfmade Backup-Solution for VPN/ISP Failover is available to secure the connection to the isp or headquarter.
		To secure a redundant gateway, policy routing (isp/vpn failover) and bgp/ospf cannot be started simultaneously.
	www.linux-vpn.de /lr101.php?s=about (299 words)

	More 1776 server failover features (Site not responding. Last check: 2007-09-15)
		When selecting server failover software, ask for the ability to control the kinds of events which will trigger a failover.
		You may want a failover to occur if a particular peripheral device or board fails, such as a communications controller.
		Another feature to look for in server failover software is the amount of flexibility in what occurs after a computer fails.
	www.1776soft.com /morefeat.htm (212 words)

	Network Computing \| Sneak Preview \| Servers & Peripherals \| Double-Take's Flexibility and Ease Make Failover a Success ...
		All clustering and failover software tends to have a fairly large performance impact, and given that a cluster is designed for high availability, server design should not be taken lightly.
		Scripting for failover entails shutting down the proper services as nicely as you can and starting them up on the corresponding target.
		During the failover process, the target machine has to do some fast footwork with re-IPing and renaming the necessary interfaces, and the GUIDs (Globally Unique IDs) used in Win2000 (previously mirrored and replicated) are set as well.
	www.networkcomputing.com /1122/1122sp3.html (1853 words)

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