It has been a difficult task to configure storage within the public clouds. Too much storage for a resource can cause problems later. Too much storage for a resource can lead to you paying extra for storage you aren’t actually using.
Amazon Web Services (AWS), however, has recently provided its customers with a tool to help with the balance between future capacity and cost. AWS makes it possible to increase Elastic Block Store storage (EBS), while it is being used. AWS customers can now size their storage to meet their current needs, without worrying about what storage they might need tomorrow.
Although it was possible to modify EBS storage previously, this required that the workload that was using the storage be taken offline. Imagine, for instance, that an administrator had decided to increase storage space to an instance that was running out of space. This process would have been done in the past by creating a snapshot of an instance, then restoring it to a new volume and attaching the new volume. The volume is not being extended but is being replaced with a larger volume. This process is effective, but it can cause downtime.
AWS allows you to change the volume size without causing downtime. Before I explain how this works, let me say that although changing the volume’s size is the most common type, it is not the only option. AWS makes it possible to tune volume performance and even change volume types while the instance is still running. Amazon CloudWatch is used by some organizations to monitor EBS volumes and make automated changes to them in response to changing conditions.
AWS makes it easy to modify an EBS volume. Log in to AWS and launch Elastic Compute cloud (EC2) to get started. Next, click the Volumes link on the EC2 dashboard. The console will display a list showing all the EBS volumes currently in use, as shown in Figure 1. The volume is displayed as in use in the figure.
[Click on the image to see a larger view.] Figure 1: The console displays a list of all the volumes currently in use. Right-click on the volume you wish to modify and select Modify Volume from the shortcut menu. Figure 2 shows you how this works.
Figure 2: Right-click the EBS volume and select Modify Volume from the shortcut menu. The Modify Volume dialog box will appear on the console. Figure 3 shows this. You will see in the figure that changing the volume is easy. Simply select the volume you wish to modify, and then click on Modify. Let’s take a closer glance at the options AWS offers.
Figure 3: The Modify Volume dialog box. The volume ID is the first piece of information the dialog box provides. Take a look at the figure. The volume ID cannot be modified, but the dialog box displays it to help you verify that you have changed the correct volume.
Next, you will see a drop-down menu that allows you to change the volume type. Figure 4 shows that you have the option of General Purpose SSD, Provisioned IOPS SSD, Cold HDD, and Throughput OptimizedHDD (ST). The options available may change over time.
Figure 4: These are the available volume types. The primary difference between the volume types is their capacity for IOPS. Here’s what each volume type currently looks like.
