AlwaysOn Failover Timings

[gary_patterson2]

Hi,

My client would like to move from failover clustering to alwayson and we've done some testing on pure SQL databases which have been positive - around 12 seconds.

Does anyone have any information, real life or becnhmark, about how SAP workload can affect the length of time taken to failover using AlwaysOn?

Regards

Gary

[luisdarui]

Hi Gary,

I would add to Sriram answer the Juergen's posts on SAP on SQL Server blog:

http://blogs.msdn.com/b/saponsqlserver/archive/tags/alwayson/

Regards,

[gary_patterson2]

Hi Luis,

thanks to both of you for your responses. I've already been through the OSS notes and Juergen's excellent blogs. I'm really looking for real life experience of failover timings using AlwaysOn in the SAP world.

The only things I can find are pretty generic such as: -

The amount of time that the database is unavailable during a failover depends on the type of failover and its cause.

and

The amount of time required to apply the log to a given database depends on the speed of the system, the recent work load, and the amount of log in the recovery queue.

Regards

Gary

[Former Member]

Hi Gary,

apart from the 2 points you mentioned above the 2 other facors that influence the failover process are

1. Amount of transaction log pending to be sent across to secondary replica for hardening

2. The network bandwidth between the Primary and Secondary node, needless to say larger the bandwidth the quicker the failover. We have had recommendations from SAP ad Microsoft to have atleast 10 GB badnwidth

so take these into account

[Sriram2009]

Hi Gary

Kindly go thru the Microsoft links & SAP note about AlwaysOn Failover cluster.

1772688 - SQL Server AlwaysOn and SAP applications

Failover Clustering and AlwaysOn Availability Groups (SQL Server)

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0CEcQFjAE&url=htt...

Regards

Sriram