Too often in the past , High Availability and Disaster Recovery have been marketed as expensive choices for businesses with deep pockets. The truth is that, with careful planning, there are sensible and economic solutions for small businesses that can maintain business continuity when disaster strikes.… Read more
SQL Server's AlwaysOn Availability Groups provide a very resilient way of providing High-availability for SQL Server databases, but there are inevitable limits to their capacity. How many databases can you reasonably add? It depends on the resources available and the workload, but you can come up with a reasonable estimate as Warwick Rudd explains… Read more
A Hyper-V replica will provide a rapid disaster-recovery by simply replicating to a standby site a VM running at the primary site. Is it, therefore, ideal for running SQL Server in high-availability? Well, it depends on the type of HA you require, and whether you need the features that aren't supported. Nirmal explains the details and shows how to set it up.… Read more
Hyper-V has become far more sophisticated since the release V3 of Windows 2012, but it means that there are now a number of alternative ways of achieving migration and High-availability. The right method depends on your particular requirements, as Nirmal explains.… Read more
High Availability (HA) and Disaster Recovery (DR) can be provided for subscription databases from an AlwaysOn Avaliability Group, but the secondary replicas will need to be manually configured to create the new subscriptions… Read more
SQL Server 2012 AlwaysOn Availability Groups provide a high-availability and disaster-recovery solution for you SQL Server 2012 environments. Replication has been around in SQL Server for quite some time and allows you to scale out your environment. Warwick Rudd explains how to join these technologies together
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It is likely that you'll want to add a database with TDS Encryption to your AlwaysOn Availability Group. If you do so you'll find that you can't use the SSMS wizard to do so. So, how do you achieve it? Read on...… Read more
If you are trouble-shooting an AlwaysOn Availability Group topology, a study of the wait statistics will give a pointer to many of the causes of problems. Although several wait types are documented, there is nothing like practical experiment to familiarize yourself with new wait stats, and Joe Sack demonstrates a way of testing the sort of waits generated by an availability group under various circumstances.… Read more
SQL Server AlwaysOn provides a high-availability and Disaster-recovery solution for SQL Server 2012. It makes use of existing SQL Server features, particularly Failover Clustering, and provides new capabilities such as availability groups. Warwick Rudd explains the basics and shows you how to implement it.… Read more
When one mailbox server in a Database Availability Group (DAG) is accidentally deleted, then it is supposedly easy to fix the problem, but if the DAG is not fully cleaned up, it can prove a little more complex.… Read more
Within an instance of SQL Server, the database settings can have a direct effect on the database's behavior, performance and availability. Sometimes, it is difficult to tie a symptom to a cause, so it is wise to routinely check and record these settings. Before you change the current setting, it pays to understand exactly what it means and the implications of any change.… Read more
Having pierced the veil of confusion surrounding High Availability, Wesley David finds himself asked (and being asked) whether HA is worth the money it burns through. Perhaps it's more cost-effective to have a recovery process that moves like greased lightning?… Read more
In Exchange Server 2010 it is possible to make the system more resilient by creating a Database Availability Group (DAG) where the nodes contain multiple server roles.… Read more
Wesley has heard High Availablity touted as all sorts of technological cure-all for busy SysAdmins and DBAs, and now he's taking a stand against it. There are a range of things that High Availability is regularly confused with (either deliberately or innocently), and Wesley's clearing it all up.… Read more
If you're using Exchange 2010, then you're probably interested in using the new Database Availability Group feature for your High Availability needs. The DAG is superbly powerful technology, but you'd better make sure yours is 100% correctly configured. Neil Hobson walks us through what we need to know, using a two-node DAG as an example.… Read more
By using a virtualized clustering computing environment with failover, you can improve server availability without using as many physical computers. A group of independent computers can work together to increase the availability of virtualised applications and services. If one of the cluster nodes fails, another node takes over to provide the service without disrupting the service. Nirmal Sharma explains the failover process under Hyper-V and how to improve the performance of a failover.… Read more
In April 2009 Microsoft released a public beta of Exchange 2010, the latest and greatest version of a part of its unified communications family of products. Recently in August 2009, a feature complete Release Candidate version was released for public download. In this article Neil Hobson takes a look at some of the high availability features of Exchange 2010.… Read more
High-Availability depends on how quickly you can recover a production system after an incident that has caused a failure. This requires planning, and documentation. If you get a Disaster Recovery Plan wrong, it can make an incident into a catastrophe for the business. Hugo Shebbeare discusses some essentials, describes a typical system, and provides sample documentation.… Read more
Neil Hobson writes about the ways that MS Exchange 2007 can ensure that your organisations messaging remains available. He looks at the way that the Mailbox Server role can be made more available using features as Single Copy Clusters, Local Continuous Replication, and Clustered Continuous Replication. He also discusses ways of improving the resilience of the other server roles.… Read more
William Brewer argues that, although there are technologies around that will minimise downtime in most circumstances, they are only part of the solution. At the heart of every robust system, there is planning, documentation, scripting, testing and drill. … Read more
