As more and more high-availability support and more and more dependability in the cloud comes into play, have your HA requirements changed?
I realize the easy answe is “Never! We need HA options to do HA right and make sure our real systems are up and available!” (Feel free to quote this in the comments). But more and more often, I’m having conversations about the types of redundancy and failover and recovery offered by the cloud and how they play into availability on the grand scale for applications.
In other words, the cloud provides a lot of really strong capability, do we still need the HA options that we’ve traditionally been fighting for for the truly critical applications and environments?
I love that the answer is becoming “it depends.” My favorite requirements answer that always seems to fit still works here.
When we coach people on recovery options and availability and all of that, the suggestions and answers always come down to what you an afford to lose (perhaps nothing) and what availability do you require (perhaps 100%). You still have to plan for and architect for supporting these objectives.
I do think that the gaps between options, in some cases, are becoming smaller and smaller. If you truly look at the Azure offerings in terms of managed databases and the whole data environment supported, it’s incredibly robust and, even without specific HA options, you may find it sufficient.
But keep in mind, if you’re relying, ultimately, on recovery if something happens, there is still a window. Still a period of time you have to address and be ok with. Make sure you know and understand these potential gaps (a restore or move to another system and restore) is still a restore. It still takes time.
In discussions I have had, and in my opinion, to answer my own question in this post – I don’t think the cloud changes your HA needs. I think it gives you additional options. I think it improves some options. It may be “good enough” in new ways that weren’t the case before. However, the same questions remain.
You have to determine your specific requirements and then really dig in to availability, recovery in the absence of availability and what it takes to put the HA solution in place for your requirements. Only you can really make that choice, and you may find it harder to find the information specifics on your options, but keep digging. Keep asking questions until you know your risks and can make a very well founded choice.