Adding a crappy backup network to your cluster

Last week, I got a really nice challenge of a customer.
They wanted to add a backup network in their 2 node cluster.
No problem, that’s pretty straight forward but… they mentioned that the backup network is crappy and unstable…
Despite that the network was unstable, they still want it to use it.

The tricky part here was that the cluster could not failover in case of a network failure of the backup LAN.
On the other hand, SQL Server must be dependent on the backup IP address if you want to use it.

This is how I worked out my solution
First of all, I added the backup IP address in my cluster configuration. I added it under the SQL Server Network Name.

At this moment, the SQL Server Network Name is now dependent on both IP addresses.
The SQL Server resource is dependent on the SQL Server Network Name, which means that it will listen on both IP addresses.
I’ve verified it by restarting the SQL Server and checked the SQL Server Log after the reboot.

So far so good. But with this configuration, a failover will occur when the backup network will go offline.
SQL Server will go offline because it’s dependent on the SQL Server Network Name, which is also offline because it is dependent on both IP addresses.
To fix this problem, I changed the dependencies of the SQL Server Network Name. Instead of being dependent on both IP addresses, only one IP address should be up and running.
I did this by changing the dependencies from AND into OR.

With this configuration, the SQL Server Network Name will stay online if the backup network goes offline.
But the reverse is also true… if the production LAN should go offline and the backup LAN stays up, the SQL Server Network Name will also stay online.
In this particular case, we want of course that a failover is initiated.

To make the failover possible, I added an extra dependency. The backup IP address must be dependent on the production LAN.

Let’s follow the chain what happens when the production LAN goes offline

backup network will go down because it’s dependent on the production LAN

SQL Server Network Name will go down because both production and backup LANs are down

SQL Server will go down because it’s dependent on the SQL Server Network Name

Failover is initiated!

 

To be sure that no failover will occur in case of restart failure of the backup IP address, I’ve unchecked the option “If restart is unsuccessful, fail over all resources in this Role” in the Policies tab of the backup IP address.

With this configuration the resource will try to restart every 2 minutes for 1 hour. If it is still not possible to restart, it will stay in a failed status.

I’ve tested this configuration really good and it’s working perfectly.

But… the real solution in this case was to get the backup network stable but this configuration is a nice workaround J

My MVP Award Story

3,5 years ago, I started working as a SQL Server DBA Consultant at Kohera. The goal that I had, next to being a good SQL DBA, was becoming a SQL Server MVP.
Many people told me that it was really hard and difficult to become an MVP, but I believed in myself that it was possible. I knew already a lot of SQL Server because of my previous job but I still had to learn a lot.
I began with reading a lot of blog posts, SQL books, forums ,… and took the exams to get Microsoft certified. I also joined the SQL User Group in Belgium to get to know the SQL people and to learn about the interesting stuff they provide in the user group sessions.

However, I was new and unknown in the SQL community world, so I started to figure out how people could get to know me.
I created a Twitter account (@Pieter_Vanhove) and started following the local “SQL guru’s” in Belgium and some of the most famous SQL guys (MCT’s and MVP’s) in the world.
I started participating in discussions on Twitter and replied on some #sqlhelp questions. Every week, slowly, I got a few extra followers. But I knew that tweeting wouldn’t be enough.

I also wanted to share my SQL experience and started this blog. I don’t blog a lot but I try to share as much as possible my SQL experience. I mostly blog interesting stuff that I have noticed in my day to day job or some interesting scripts that I’ve created.

After a few months, I was asked by Microsoft if I wanted to give a Technet Live Meeting. Sure, why not! The goal of this is to provide an online session that people can join on the web. It was actually my first speaker experience, although it was not in front of a live audience.
As a result of these live meetings, I was selected to join the Microsoft Extended Expert Team (MEET). All MEET members are Belgian experts which have been selected for their skills and knowledge in their area of expertise. They all share their knowledge via their blogs and are regular speakers at Microsoft events or User Group meetings.

After one year, I got a question of the SQLUG if I would like to give a session on SQL Server Days. This is *the* SQL event in Belgium every year. Of course I did and I was really excited about it, my first session in front of a live audience! It was great and it tasted like more. So I’ve started speaking at other events like Community Day, 12 hours of SQL Server 2012, SQLUG sessions and Microsoft Discovery day. I tried already a few times to speak at international events like SQLBITS or SQL PASS Summit, but I never got selected… (maybe this year 😉 ) I didn’t gave up and I wanted to see how my chances are to present on a SQL Saturday event. So I submitted a few sessions for SQL Saturday in Slovenia and guess what, I got selected!!

And last but not least, this year I joined the SQL Server Days group to help organizing the biggest SQL Event of the BeNeLux. It was again a really great experience.
I met a lot of nice people from the SQL community (or SQL Family as they call it), like Thomas LaRock (Twitter|Blog), Kevin Kline (Twitter|Blog), Mark Stacey (Twitter|Blog), … and they gave me some really good advice and tips.

A few weeks later, I got nominated for the MVP Award and on the 1st of January 2014 I got and E-mail from Microsoft starting with

Congratulations! We are pleased to present you with the 2014 Microsoft® MVP Award!

I also would like to thank all the people who supported me and believe in me!