What is cross-region replication
For anyone reading this that doesn’t know what ANF is; it’s a Microsoft shared file service that is native to Azure (first-party). That means it’s supported and sold by Microsoft themselves, just like premium and ultra managed disk.
Now that’s out of the way let’s get to the exciting news: Cross-Region replication is now available in private preview for customers within certain regions (reach out to your local CSA to find out the latest news on your specific region). This is a big-deal for anyone using ANF and needing powerful, yet simple to manage disaster recovery in Azure.
How does it work?
Cross-region replication uses block-level tracking making it the most efficient replication technology available in Azure today. This is important as it results in much reduced data payload for replication, which directly reduces data egress and therefore cost of regional replication.
The configuration is relatively straight forward. If you haven’t already, create a volume that will be used as the source of the replication, you can use an existing volume with existing data if you already have one.
For this demonstration we will be using a 1TB volume called primary-vol as the initial source volume in eu-north, and we will create a destination volume called secondary-vol in eu-west. CRR (Cross-Region Replication) will then be configured on a 10-minute asynchronous schedule to ensure data is frequently replicated between regions.
Simpler architecture, less operational complexity and also more cost efficient
That’s a brave claim – simpler, easier and cheaper? Let’s put that to the test:
Simple Architecture: No VMs to deploy or keep switched on for replication – also no VNET peering to configure. In addition, when using VMs there is the added complexity of having to maintain, patch and right-size (bandwidth calculations) for your replication needs. None of this architecture is required when using ANF.
Less complexity: All networking is already provided by the service. Therefore you do not need to setup global VNET peering or VNET gateways as all replication uses the Azure backbone itself for maximum performance.
Cost efficient: By removing the need for VMs to replicate data you can remove these (where appropriate) or switch them offline until DR is invoked. This can save significant monthly spend in many cases. Please note: whilst CRR is in preview – there is no cost for data replicated by the service – use this to your advantage to seed your entire DR site for free (you’ll still pay for the volumes themselves of course!)
How do I invoke DR? How fast can I failover?
A major benefit of CRR is that failover takes seconds – that is, the data can be made available for read and write (this is important – the data is always available for read at the secondary site). This is done with one simple ‘break replication’ command.
Difference between ultra/premium/standard tiers?
ANF is available in three different tiers – Ultra, Premium and Standard. Regardless of the tier you select, all will benefit from accelerated and efficient replication at similar speeds shown above.
You may now be wondering how CRR compares to other replication technologies such as RSYNC, Robocopy, XCP or even NetApp’s own CloudSync solution.
That’s it for this week. Be sure to join me for part 2, where I directly compare the time taken to replicate 1TB of data between regions using several different technologies.