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minimum bandwidth/network requirements for AlwaysOn

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Wednesday, August 1, 2012 7:50 PM

I have been asked to look into a HA solution for SQL and I immediately thought of AlwaysOn in 2012. The biggest hurdle though is that the cluster would have nodes in two geographically separated data centers. I'm not sure what the minimum connection speed is at the moment but they are complaining about log shipping timing out. In the past this simply wasn't supported in MS clustering but now they claim it is with 2012. Is there documentation on the type of connection or amount of bandwidth you need at a minimum to have a successful cluster in 2012? 

All replies (3)

Thursday, August 2, 2012 6:59 AM âś…Answered | 1 vote

The simple answer is: You need to look on your log generation rate... If you generate 1 MB of transaction log per second, you need 1 MB of bandwidth to satisy the AlwaysOn requirements.

One difference to LogShipping is that the packages themselves are way smaller. This means that on slow or unstable connections you have a higher success rate with AlwaysOn. But still... You need the bandwidth as described above.

Sidenote: Chad is of course right that the traffic will be compressed, so the actual bandwidth need will be a little less than that... But with protocol overhead etc. going for the full generation rate as bandwidth is most of the times a good idea...

Wednesday, August 1, 2012 8:07 PM

Hi,

If log-shipping is timing out, I wouldn't expect AlwaysOn to work on a reliable way.

Sebastian Sajaroff Senior DBA Pharmacies Jean Coutu

Wednesday, August 1, 2012 9:18 PM

Are the log backups compressed with your log shipping implementation? One thing to note with AlwaysOn as it was build on the mirroring infrastructure, the log stream will be compressed as if travels to the secondaries so you may see a gain of your log shipping backups were not compressed.

Also when you say log shipping is timing out, is that on the copy or the restore job?


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