Cloud Services: Migration Experience

Why does the migration method depend and how to make everything work and not cost a pretty penny?

Let’s imagine a cloud in the form of an apartment or a house. Then IaaS is bare housing without renovation. You can’t live in it. At the same time, a ready-made working system that everyone uses, or SaaS, is a ready-made apartment with furniture, in which it is not a shame to move in and invite guests. In this case, we and our guests are system users who, in addition to furniture, need things, kitchen utensils, etc. In other words, we brought with us the data that we store and use in the system.

To migrate somewhere, that is, to transfer our things, we need everything there to be ready for this. So that there are not only walls, but also cabinets, doors, an equipped bathroom, etc. Therefore, during migration, as well as when moving, preparation takes most of the time, and the migration itself usually takes one day, night or a couple of hours.

First, let’s look at the easiest way to migrate – from one cloud provider to another.

We prepare a plan and determine the migration method. You can clone virtual machines, you can deploy them from a backup, you can bring up everything new and transfer the databases. Let us consider the last option as an example, since the migration method in this case will be very similar to migration from your own equipment or to a private cloud.

First, we need to get the infrastructure. A cloud provider is ready to help make the right sizing, but often the same number of virtual machines is allocated as an existing provider. This is done so that in the presence of errors, you do not get two paths in which you will need to look for the problem.

Then the platform is being prepared. Software is installed on virtual machines – operating systems, database management systems, security tools and other programs. The software is usually configured according to the resource-service model, or the settings are simply copied from the existing system.

After these two steps, consider that your new apartment is ready to move in. Readiness is best confirmed by functional and load testing. Usually the described two stages take a very long time – from two weeks to a year.

Data, unlike things, can be transferred in parts. First, transfer most of the data, and then, by turning off the old site, so that guests do not change or transfer information, “catch up” with the remaining changes. The transfer of the last part of the data, which requires a complete system shutdown, usually does not take more than 8 hours, and it strongly depends on the volume and the chosen migration technology. The fastest migration required disabling the main service for only 15 minutes.

That’s all, you can celebrate housewarming.

In total, for migration you need:

1. determine the migration method;
2. prepare a plan;
3. allocate and configure infrastructure;
4. install and configure the platform;
5. test;
6. transfer data;
7. turn off the old one and turn on the new one;
8. check the performance and in case of problems immediately return to the previous site, start all over again.

In terms of cost, many providers, including Onlanta, migrate to their own public cloud for free.