High availability

SQL Server AlwaysOn availability groups and statistic issues on secondaries

I would like to share with you an interesting issue you may face while using SQL Server AlwaysOn availability groups and secondary read-only replicas. For those who use secondary read-only replicas as reporting servers, keep reading this blog post because(…)

SQL Server 2016: Distributed availability groups and Cross Cluster migration

How to migrate an environment that includes availability groups from one Windows Failover Cluster to another one? This scenario is definitely uncommon and requires a good preparation. How to achieve this task depends mainly of your context. Indeed, we may(…)

SQL Server AlwaysOn: troubleshooting improvements with new service packs

As promised in my latest blog, I will talk about improvements in the detection of the availability group replication latency. As a reminder, replication latency between high(…)

SQL Server 2016 AlwaysOn: distributed availability groups

This time, I will talk about distributed availability groups. What’s that? In short, a group of availability groups. Sounds good right? But in which cases may we need such architecture? Firstly, let’s say that(…)

SQL Server AlwaysOn: is my database ready for failover?

In this blog post I just want to clarify values that we may find from the is_failover_ready column of the sys.dm_hadr_database_replica_cluster_states DMV. A couple of days ago, I had an interesting discussion with one of my customers during which he(…)

Windows Failover Cluster : Introduction to paxos tag

A couple of days ago, I was in charge to install a new SQL Server AlwaysOn and availability group with one of my colleague Nathan Courtine. During the installation, we talked about testing a disaster recovery(…)

Windows Server 2016: Introducing stretch cluster functionality

Let’s continue with the new high available functionality shipped with the next Windows version. In my previous blog, I talked about the new site awareness feature that provides more flexibility to configure failover resources priorities and(…)

SQL Server AlwaysOn: when a listener becomes the cluster and vice versa

Let’s talk about a funny story that concerns an interesting issue that I faced a couple of months ago at one of my customers. Initially, the problem concerned only the creation of an availability group listener but after deleting the(…)

The dbi services PostgreSQL reference architecture (2) – The community approach

In the last post I looked at how dbi services designs a PostgreSQL architecture based on the products of EnterpriseDB. In this post I’ll look at the same questions but using pure community tools. If you(…)

The dbi services PostgreSQL reference architecture (1) – The commercial approach

When it comes to designing a PostgreSQL architecture that fits your requirements there are a couple of things to think about: Do you need a HA setup? How shall backups and restores being done and how shall all of these(…)