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How is RHEL in the cloud different than in the data center?
Implementing RHEL in the cloud isn't exactly the same as using cloud technology in the data center, especially when addressing swap and support concerns.
There are some subtle differences between how RHEL works in the cloud and how you might be familiar with using it in a traditional data center.
In a cloud environment, you don't install virtual machines; you deploy them, but configuration options are limited. You select one of the available images, apply hardware properties to it and boot up the cloud instance. There is no easy way to work with features such as custom partitioning, and you're more restricted if you work with default cloud images.
There is a way to use custom configurations -- you can build your own custom images and use them with RHEL in the cloud -- but it's a completely different approach than installing the instance and selecting which features you want to use.
Another difference between an installed version of Linux and RHEL in the cloud is the boot procedure. In the cloud, Linux doesn't boot from a disk boot sector using Grub; the cloud boots it. As a result, you can't access the boot menu to fix problems. Instead, you must use your cloud providers' tools to fix startup problems. And if these tools don't meet your needs, you must redeploy the virtual machine.
To synchronize cloud-imposed configuration to the virtual machine, the virtual machine will typically run an agent, which enables the cloud to interact with the software features of the virtual machine.
Swap and support concerns
From a technical point of view, there are some significant differences, as well. For example, you might be used to configuring swap space on Linux servers, but using swap doesn't make sense in a cloud environment. Typically, you'll work on Linux instances that don't have any swap configured.
The next item to consider when using RHEL in the cloud is where support will come from. You will deal with your cloud provider because it provides the platform, but Red Hat is the OS provider.
Take AWS, for example: Most customers purchase RHEL through AWS, but Red Hat also offers Red Hat Cloud Access, which enables current Red Hat customers to run RHEL in the cloud. In both cases, you receive access to Red Hat patches when they are released.
If you need help solving any RHEL issues and you purchased Elastic Compute Cloud instances through Red Hat Cloud Access, you will go to Red Hat directly for support. All other customers get support through the AWS premium support offering.
These features are the most significant differences you will encounter while working with RHEL or any other Linux distribution in the public cloud. Once you get the right image up and running in your public cloud, it will be mostly business as usual.
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