Let’s say that you identified some IBM i workload that you would like to move to the cloud. You’ve already gone through a sizing exercise to understand how much resource you will require. Now you’re wondering how to migrate your application and associated data to the cloud.
Good news! You have several options to choose from. We’ve described a few of them below (in no particular order) and have listed the pros and cons for each.
Option #1: Full Save and Restore
This is a multistep process that can be described as a clean way to migrate to cloud.
First, you must take your users off the system. Then, you need to terminate all subsystems to bring it to a restricted state. Lastly, you’d perform a full system save (SAVSYS, *NONSYS, SAV, and SAVDLO) using either the manual GO SAVE option 21 or a tool such as BRMS or Robot Save.
But whether you use physical tapes or the more modern virtual tape library (VTL), there are a few drawbacks to this option:
- The save (and restore) will typically take an extremely long time.
- No access to the application activity is allowed while the save / restore is being conducted.
- There is no facility to test the mechanism to verify how long an outage you will require.
If you have the luxury of being able to handle a large outage window (think hours or even days), this option could be for you—at least for development or test partitions.
Option #2: Full Save and Restore + Partial Save and Restore
If the large outage window described above is not feasible—and, let’s be honest, for many it will not be—there is an alternative. A full system save is still required but, once complete, users could be allowed back onto the source system. The restore onto cloud infrastructure can then take place.
At a future time, you’d need to administer a backup of any changes made. These changes can be captured via incremental or differential backup methods (again, with the users off) before being restored to the cloud. Users would need to remain off the system until such as a time as the cloud instance is fully operational.
When compared to full save and restore, this option reduces the outage time, but it does increase the number of steps that your system administrator would need to take.
Option #3: Logical Replication
Logical replication solutions are built on top of remote journaling—an integral of the IBM i operating system—and have been a mainstay in many IBM i environments for many years now. Logical replication software like Robot HA offers data synchronization between on-prem and cloud as well as between on-prem systems and cloud systems with very little or no downtime whatsoever.
The initial synchronization between the source and target servers can be done via save and restore. Once complete, a manual synchronization point can be defined for each group of data libraries. Any journal transactions after this point would be applied in order.
Alternatively, Robot HA can perform an initial save-while-active before sending the data to the target server, again keeping the data up to date via remote journaling.
A huge advantage with using logical replication is that there really isn’t an outage as all transactions are replicated in real time or near-real time. This allows the business to conduct both data integrity and application latency testing to ensure that the cloud migration has been a success. Logical replication can continue to run until such a time that you are ready to cut over to cloud and can continue long after for HA/DR purposes.
Feed Two Birds with One Scone
With many IBM i shops having their target partition at a managed service provider (MSP) or in the cloud, the most efficient way to achieve high availability is via logical replication tools.
Robot HA has flexible licensing options designed to cater for those environments purely looking for a tool to help migrate to cloud. It is also very easy to set up! You can be replicating data within 30 minutes of installation.
24/7 business demands 24/7 system and application availability. When you’re ready to avoid downtime—be it planned or unplanned—Robot HA is the fastest, easiest, most affordable way to establish high availability at your organization.