Organizations migrate on-premises storage into a cloud storage-as-a-service environment for a number of reasons. The migration may be mandatory because of a merger or acquisition, in which data from another organization has to be migrated to a new or existing environment, or because your business segment has been sold, which requires you to migrate storage elsewhere. In many cases, migration is voluntary in a quest for better service delivery. Cloud services can cut costs, increase flexibility and in some cases, ensure better service performance.

Your migration can be handled in one of three ways: big bang, parallel, and phased. Let’s take a look at the pluses and minuses of each.

Big Bang Migration

Big bang migrations move data to the new location and immediately direct users to access data elsewhere. It’s the proverbial ripping off of the Band-Aid in which everyone starts something new all at once instead of slowly migrating over. The frustrations that are inevitable with any migration are intense, but you get them out of the way in a contained time period (hypothetically speaking). The costs tend to be lower, and you avoid dealing with intermediary solutions or using two operating systems at once.

The bad news about big bang migrations is that they’re high risk. Failure can lead to long periods of downtime and intense frustration as users are corralled into a new system all at once. Big bang migrations can work well if companies are moving only small amounts of data, or if they’re migrating data from only a few offices. A large transition performed big bang style can lead to major interruptions, which most organizations can’t afford.

Parallel Migration

Parallel migration sets a complete new storage-as-a-service environment that runs concurrently with the old on-premises storage. The two environments run side-by-side until the organization is ready to switch the old one off. Parallel migration mitigates risk somewhat since the old environment stays functional while the parallel environment is established.

It may be worthwhile to run both on-premises storage and remote storage-as-a-service arrays concurrently for applications that you’d have to recover very quickly and with minimal data loss. Establishing and managing two complete environments at once, however, gets expensive, in terms of both infrastructure usage and personnel costs, so migrating everything in this way gets cost prohibitive very quickly.

Phased Migration

phased migration

Phased migration, also called iterative migration, migrates your stored data over incrementally until you’re fully up and running in the cloud. You can migrate one or a few offices at a time, or you can start with applications that have few or no interdependencies. Phased migration gives users a chance to get used to new ways of doing things and gives you time to figure out hiccups as you go without the risk that comes with big bang migration. It can also be more complex to manage as you bridge old and new storage to keep applications functional while you transition.

For a deeper dive into phased migration with VPSA Storage Array, check out our case study: VPSA in the Cloud. The quick summary is that VPSA Storage Array makes it easy to asynchronously replicate data, whether you’re replicating to a different pool within the same VPSA Storage Array, to a remote VPSA Storage Array (either within your Zadara Cloud or to a completely different geographic location) or to a completely different cloud provider. Data is written to your local VPSA storage array in real time and then, asynchronously and in the background, it’s replicated to a remote VPSA Storage Array.

In addition to being a great disaster recovery and backup solution, this per-volume remote mirroring creates a natural, seamless phased migration. Because replication is snapshot based, only data that’s changed gets replicated, and only the most recent change is synchronized, which saves bandwidth and ensures minimal service performance impact. When all volumes are migrated to the cloud, you can start running your new workloads there.

Choosing the Right Mix

Most migrations involve some mix of big bang, parallel and phased. The right balance depends on your budget, your timeframe, and your risk threshold. Our VPSA Storage Array is designed to make phased migration easier and more cost-effective, giving you a way to control costs without introducing the risk that comes with moving everything overnight. For more information about the advantages gained with Zadara’s VPSA Storage Array, read the case study.