Unlocking Performance: Direct Storage Mapping with Oracle OLVM

 

Intro 

Virtualization is far from dying - in fact, cloud computing wouldn’t exist without it. In my view, virtualization was the real game-changer that opened the gateway to the cloud. While the cloud has been widely adopted, many organizations are now moving to hybrid cloud strategies to balance flexibility and control.

The recent resurgence in virtualization interest is largely due to Broadcom’s acquisition of VMware, which introduced new licensing models that pushed many small and medium-sized businesses to explore alternatives.

In my opinion, Oracle Linux Virtualization Manager (OLVM) stands out as the most viable option. Oracle has been in this space for years, providing robust support and continuous innovation. I recently discovered that OLVM now supports direct storage mapping, allowing workloads to bypass the hypervisor layer and write directly to storage, a major performance advantage for demanding enterprise environments.

We’ve seen many small and medium-sized businesses use OLVM to run their Oracle databases. When a database requires higher storage throughput, OLVM provides an excellent option to optimize storage performance via direct mapping.

In this article, I’ll demonstrate how easy it is to integrate storage using Direct Mapping in OLVM.

Before diving into the implementation steps, let’s first highlight a few disadvantages of using Direct Mapping:

• Limited Portability:
  VMs using Direct LUNs are tightly tied to specific storage, making live migrations between hosts more complex.

• Backup and Snapshot Limitations:
  Direct LUNs bypass the standard OLVM storage domain, so built-in snapshot and backup features may not be available.

• Management Complexity:
  Each LUN must be manually mapped and managed, which increases administrative overhead compared to managed storage.

• Reduced Flexibility:
  Since the LUN is directly attached, it cannot be easily cloned, resized, or moved across environments.

• Dependency on Storage Configuration:
  Any misconfiguration or change on the storage side can directly impact VM availability and performance.

Now, navigate to Compute > Virtual Machines > Select the VM > Disks to begin the configuration.

                                                Figure 1: Navigate the storage disk

Once you select a disk, you’ll see three main options:

• Image (VM Disk)

• Direct LUN

• Managed Block

Next, go to the Direct Mapping tab and choose the appropriate host. You’ll then need to select the storage type, which can be one of the following:

• iSCSI

• FC (Fibre Channel)

                                                       

                                                      Figure 2: Add da irect mapping disk

In this example, we’ll add a storage type of FC. Once you change the storage type to FC, the system will display the available Fibre Channel disks. Before adding, verify the correct LUN ID with your storage administrator to ensure proper mapping.

                                                    Figure 3: Select disk 

You can now use the fdisk command to partition the direct-mapped disk.

After adding the direct mapping, you can verify the configuration by selecting the Disk Type: Direct LUN to confirm the mapped LUN is correctly attached.

                                              Figure 4 : Validate the direct mapping disk.

Conclusion

Direct mapping in Oracle Linux Virtualization Manager (OLVM) offers a powerful way to achieve higher storage performance by allowing VMs to access storage directly, bypassing the hypervisor layer. While it introduces some management and flexibility trade-offs, it’s an excellent option for workloads, especially Oracle Databases that demand low latency and high throughput.

By understanding both the advantages and limitations, administrators can effectively leverage direct mapping to optimize storage performance while maintaining a stable and efficient OLVM environment.