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High availability Archives - Blog dbi services

David Barbarin

SQL Server Failover Cluster on Linux and synchronizing uids/gids across nodes

By | Database Administration & Monitoring | No Comments

In my previous blog post, I talked about SQL Server on Linux and high availability. During my test, I used a NFS server to share disk resources between my cluster nodes as described in the Microsoft documentation. A couple of days ago, I decided to add a fourth node (LINUX04) to my cluster infrastructure and I expected to do this work easily. But no chance, I faced a problem I never had before on this…

 
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David Barbarin

SQL Server AlwaysOn – Distributed availability groups, read-only with round-robin capabilities

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  This blog post comes from a very interesting discussion with one of my friends about the read-only capabilities of secondary replicas in the context of distributed availability groups. Initially, distributed availability groups are designed to address D/R scenarios and some migration scenario types as well. I already discussed about of one possible migration scenario here. However, we may also take advantage of using secondary replicas as read-only in Reporting Scenarios (obviously after making an…

 
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David Barbarin

Introducing high-availability and multi-subnet scenarios with SQL Server on Linux

By | Database Administration & Monitoring | No Comments

On my first blog about SQL Server on Linux, I introduced the new high availability feature which concerns only SQL Server failover cluster instances so far. During this discovery time, I had the support of Mihaela Blendea (@MihaelaBlendea) at Microsoft to clarify some architecture aspects about this new kind of architecture. Firstly, I would like to thank her. It’s always a big pleasure to get the availability of the Microsoft team in this case. But after…

 
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David Barbarin

Introducing high-availability with SQL Server on Linux

By | Database Administration & Monitoring, Database management | No Comments

A couple of months ago, I did my first installation of SQL Server on Linux. I wrote about it in this blog post. So now it’s time to start the new year by talking about high availability on Linux with SQL Server vNext. Running standalone instances will be suitable for scenarios but I guess introducing high-availability with critical environments still remain mandatory.Currently, the CTP1 supports installing a SQL Server Failover Cluster Instance on the top…

 
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David Barbarin

Dealing with WSFC 2016 quarantine state and availability groups

By | Database Administration & Monitoring, Operation systems | No Comments

I was playing with my lab environment which includes Windows 2016 and SQL Server 2016 and I noticed an interesting scenario while testing cluster node failures. After simulating some network outage scenarios, I was not able to bring back my cluster node online immediately by using traditional way. A quick look at the cluster manager led me to notice something new: A quarantined state value … interesting! But what does it mean exactly? In respect…

 
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David Barbarin

MS Cloud Summit Paris 2017

By | Database management | No Comments

Une nouvelle année commence et 2017 devrait être un bon cru dans le domaine de la base donnée notamment en prédiction des effets d’annonces faites par Microsoft cette fin d’année 2016. En effet, il a été notamment été question de la prochaine vNext de SQL Server qui sera porté sous Linux ainsi que des nouvelles fonctionnalités prometteuses. A l’habitude, l’équipe dbi services tentera couvrir les différents sujets au cours cette année. N’hésitez pas à revenir de temps en temps…

 
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David Barbarin

Migrating your existing availability group infrastructure to 2016

By | Database Administration & Monitoring | No Comments

Have you already a plan to migrate your old SQL Server 2012 availability group infrastructure to windows 2016 and SQL Server 2016? In a previous post, I talked about distributed availability groups and cross-cluster migration scenarios but this time the game is not the same because we want to achieve an in-place upgrade of the existing AG infrastructure. This question will probably be a concern the next year and if we take a closer look…

 
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David Barbarin

SQL Server 2016: distributed availability groups and cascaded replicas

By | Database Administration & Monitoring | No Comments

During the last MVP summit, we had some interesting discussions about availability groups with the SQL Server team and I remember someone asked for managing scenarios like Oracle cascaded destinations and the good news is that SQL Server 2016 already addresses this kind of scenario with distributed availability groups. For example, let’s say you have to manage heavily reporting activity on your application and a solution would be to offload this activity across several secondary…

 
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David Barbarin

SQL Server AlwaysOn availability groups and statistic issues on secondaries

By | Database Administration & Monitoring | No Comments

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 it is about update statistics behavior on the secondary replicas and as you may know cardinality estimation accuracy is an important part of the queries performance in this case. So a couple of days ago,…

 
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David Barbarin

SQL Server 2016: Distributed availability groups and Cross Cluster migration

By | Database Administration & Monitoring | No Comments

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 use a plenty of scenarios according to the architecture in-place as well as the customer constraints in terms of maximum downtime allowed for example. Among all possible scenarios, there is a process called “cross-cluster migration…

 
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