In the past few articles I’ve been covering the issues around moving your database from on-premise servers to the cloud. And there are definitely a lot of issues to be concerned about. In my last article I dug into the areas of latency and security but there are a host of other issues to be concerned about as well including the type of cloud implementation (IaaS, PaaS DBaaS), performance, geographical ownership of data and the last mile problem. While its clear that the cloud is certainly becoming more popular it’s also clearly not an inevitable path for everyone. Even so you shouldn’t necessarily seal the cloud off in a box and forget it for the next five years. Cloud technologies have evolved quickly and there are places where the cloud can be a benefit – even to IDBAs and IT Pros who have no intension of moving to the cloud. In this article I’ll tackle the cloud database issue from another angle. Where does using the cloud make sense? There are a few places where the cloud makes sense: disaster recovery (DR), availability, new infrastructure. Let’s take a closer look at each.
Off-site backups are an obvious area where the cloud can be a practical alternative to traditional off-site solutions. For regulatory and disaster recovery purposes most businesses need to maintain an offsite backup. These backups are often still in tape format. Maintaining an offsite storage service is an expense and there isn’t immediate access to the media. Plus, there is a high rate of failure when performing restores from tape. Moving your offsite backups to the cloud can address these issues. The cloud is immediately available plus the digital backup is more reliable. Of course since connection latency is more of an issue with the cloud than it is with on-premise infrastructure one important consideration for cloud-based backups is the time to backup and to restore. The backup time isn’t so much of an issue because that can be staged. Cloud restores can be speed up by utilizing network and data compression or low latency connections like ExpressRoute.
DR and HA
One of the places where the cloud makes the most sense is in the area of disaster recovery. The cloud can be a practical and cost effective alternative to a physical disaster recovery site. Establishing and maintaining a physical DR site can be a very expensive undertaking leaving it out of reach for many smaller and medium sized organizations. The cloud can be an affordable alternative for many of these organizations. Various types of technologies like Hyper-V Replica, VMware Replication and various third party products can replicate your on-premise virtual machines to cloud-based IaaS VMs. This enables you to have near-real time VM replicas in the cloud that can be enabled very rapidly in the event of a disaster. This type of solution leverages cloud storage and provides a disaster recovery solution that your normal day-to-day operations do not depend on. The cloud is utilized for off-site storage and possibly a temporary operations center if your on-premise data center fails.
Another closely related area is application availability. Technologies like SQL Server’s AlwaysOn Availability Groups can protect your on-premise of even cloud databases by using cloud-based VMs as asynchronous secondary replicas. For instance, you could setup a SQL Server AlwaysOn Availability Group that had synchronous on-premise secondary replicas that provided automatic failover and high availability and at the same time have asynchronous secondary replicas in Azure. If there was a site failure or a problem with the synchronous replica then the asynchronous replicas in Azure can be manually failed over to over with little to no data loss.
Another area where the cloud makes sense is for startups or other smaller businesses that are in need of an infrastructure update. For businesses where there’s no existing infrastructure or businesses that have aging infrastructure that needs to be replaced buying all new on-premise infrastructure can be a significant expense. Taking advantage of cloud technologies can enable business to get up and running without needing to capitalize a lot of their equipment costs.
Cloud technology still isn’t for everyone – perhaps especially not for DBAs and database professions -- but there are still areas where it makes sense to leverage cloud technologies.