Re: High Availability

From: Jason Buffington (jasonbuffington_at_hotmail.com)
Date: 07/28/04 

Date: Wed, 28 Jul 2004 00:57:51 -0500

another option would be to use an asynchronous replication software that
also does failover.

Async replication is real-time, as opposed to the scheduled Log Shipping
function, which reduces the latency of the data.

And for availability, you can failover similar to a cluster (assuming a
server name, IP and starting services) without the distance limitation.

Check out Double-Take by NSI Software - here is a link to their SQL
whitepaper.
http://www.nsisoftware.com/pro/white/

jason

"Uttam Parui[MS]" <uttamkp@online.microsoft.com> wrote in message
news:qhGiyIlYEHA.2688@cpmsftngxa06.phx.gbl...
> 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
>
> This posting is provided "AS IS" with no warranties, and confers no
rights.
>
> Are you secure? For information about the Strategic Technology Protection
Program and to order your FREE Security Tool Kit, please visit
http://www.microsoft.com/security.
>
> Microsoft highly recommends that users with Internet access update their
Microsoft software to better protect against viruses and security
vulnerabilities. The easiest way to do this is to visit the following
websites:
> http://www.microsoft.com/protect
> http://www.microsoft.com/security/guidance/default.mspx
>
>