Re: High Availability

From: Uttam Parui[MS] (uttamkp_at_online.microsoft.com)
Date: 07/05/04 

Date: Mon, 05 Jul 2004 05:36:59 GMT

Note that one of the considerations for the active/passive GEO Cluster is that the network connections must be able to provide a maximum guaranteed round trip latency between nodes of no more than 500
milliseconds. The cluster uses heartbeat to detect whether a node is alive or not responding. These heartbeats are sent out on a periodic basis (every 1.2 seconds). If a node takes too long to respond to
heartbeat packets, MSCS starts a heavy-weight protocol to figure out which nodes are really still alive and which ones are dead; this is known as a cluster re-group. The heartbeat interval is not a configurable
parameter for the cluster service (there are many reasons for this, but the bottom line is that changing this parameter can have a significant impact on the stability of the cluster and the failover time). . 500 ms round-
trip is significantly below any threshold to ensure that artificial re-group operations are not triggered

You may want to research SQL Server Replication/ Log Shipping if you can have some latency (few secs).

Addtional Information:
=====================

http://www.microsoft.com/technet/prodtechnol/sql/2000/maintain/default.mspx

SQL Server 2000 High Availability Series
Plan and deploy a highly available data center that uses SQL Server 2000. This guide covers procedures to help you increase availability of your servers, recover from catastrophic disasters, and prevent and
minimize downtime.
 
SQL Server 2000 Failover Clustering
Understand how failover clustering works and how to implement, administer, and troubleshoot a failover cluster. Also included: worksheets and checklists to assist you during installation.
 
Log Shipping in SQL Server 2000 - Part 1
Increase your SQL Server availability by setting up, reconfiguring, and monitoring log shipping, which is supported in both SQL Server 2000 Enterprise Edition and SQL Server 2000 Developer Edition.
 
 Log Shipping in SQL Server 2000 - Part 2
Find out how to change the roles of the primary and secondary servers, how to fully reverse their roles, and where to place the monitor server for the most effective monitoring.

Replication Overview
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/replsql/replover_694n.asp

Typical Uses of Replication
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/replsql/replintro_6trn.asp

How Replication Works
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/replsql/replintro_6trn.asp

Planning for Each Type of Replication
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/replsql/replplan_82zy.asp

Transactional Replication and Log Shipping
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/replsql/replbackup_3js7.asp

Microsoft SQL Server 2000: The Types of Replication and When to Implement Each
http://support.microsoft.com/default.aspx?scid=kb;EN-US;818714

 Introducing New Features in Microsoft SQL Server 2000 Transactional Replication
http://support.microsoft.com/default.aspx?scid=kb;en-us;324966

Best Regards,

Uttam Parui
Microsoft Corporation

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