Sql server clustering the pertinent choice

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SQL Ser ver Clustering – the Per tinent Choice By SPEC INDIA


What is SQL Ser ver Clustering?  One or more “clustered” SQL instances on one or more physical

servers running MS Windows is termed as SQL Server Clustering.  In order to get a larger availability for SQL server database, the apt

solution is to store them on server clusters using the SQL Server Clustering Service.  Such configured servers share their similar information and

together operate as a single system.  The independence of each individual server is retained and hence if

there is a failure in one server, there is presence of another server to take over the former’s responsibilities.


What is SQL Ser ver Clustering?  There are multiple nodes in a single setup, in which individual

nodes have their own memory space, disk space and OS.  In case of failure of one node, there is another one ready to take on

the former node’s responsibility. In such cases, what the SQL Server clustering service does is it registers the network address of the resource on the latest node so that the entire traffic is redirected to the latest server.  Once the server that was down, is brought back upright, the cluster

service can be reconfigured along with resource redistribution.


Types of SQL Ser ver Clustering Techniques


Types of SQL Ser ver Clustering Techniques  There are three different types of SQL Server Clustering

techniques as depicted above, depending upon your requirements and cost factor.  It is also possible to have your server configuration change

based on the usage of the server.  If you wish to have both servers execute applications, they

will be in active mode and will run applications as well as take backup.  The other option is in which one server will be running

applications and the other one will take backup.


Types of SQL Ser ver Clustering Techniques  Shared Disk  This technique is such that in this, multiple server will be sharing the same disk.  It does not need costly cables and switches, but do need typically modifiable

applications with the use of a software called the DLM (Distributed Lock Manager).  Mirrored Disk  This technique talks about each server having its own disk with the use of a

software that mirrors each and every step from one server to the other.  It is considered having better flexibility than the earlier technique.  It is also considered to be helpful in having data at a disaster recovery site which is

in synchronization with a primary server.


Types of SQL Ser ver Clustering Techniques  Shared Nothing  In this type of a configuration, the server has ownership of its

own disk resources.  In case of failure of a server, the shared nothing cluster would

have software which would transfer the ownership of a disk from a server to yet another.  It gives a similar level of availability as the first option, but with

a little higher level of scalability, the reason being, it does not possess the hurdle of a DLM.


Prime Benefits of SQL Ser ver Clustering  Higher availability of data and higher chances of applications remaining online  Availability of different nodes in case of hardware failure on the primary server  Easy applicability of security patches on servers with the help of clustering,

leading to very limited downtimes while moving the SQL server instance from one node to another  Access to a spare tool / node while troubleshooting, in case required to test  Transparency to the calling application  Many components like databases, logins etc. are easily workable with SQL

Server Clustering


Points to take care of while SQL Ser ver Clustering  Determine appropriate naming convention for various elements

in the cluster  Put limited nodes in a single cluster, preferably around 2-3  Test your application thoroughly after migration to a cluster  Keep evaluating your SQL Server Clustering setting regularly  Have powerful servers in usage since clustering won’t improve

performance in case the servers are not that upgraded  Focus on maintenance equally as clustering will not be able to

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