Single‑tier LUNs have QoS properties that specify the Storage Class and other performance parameters for storing data on the LUN on the Oracle FS System.
The QoS properties of a single‑tier LUN remains unchanged until the administrator changes these properties. An auto‑tier LUN monitors the data activity and automatically adjusts the QoS properties based on system performance and data activity. For some applications, you might not want the Oracle FS System to make changes to your QoS properties. In this case a single‑tier is preferred.
Your application requires low latency for all I/O. A single‑tier allows you to specify the Storage Class, such as a Performance SSD. Specifying the Storage Class ensures that the system uses this class regardless of the access frequency by your application.
Your application is accessed frequently but has no particular performance requirement. A single‑tier allows you to isolate your long-term data to a high‑capacity drive, which has regular performance characteristics.
You are migrating an application from an existing system to the Oracle FS System and the existing system has LUNs configured for specific performance requirement of your applications.
If needed, you can change the tier type to auto‑tier after you create the LUN.