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Typically, a Dell Unity system is used to service multiple hosts and applications. These applications can have different service levels and different storage demands. In addition, a single array can provide services to multiple environments such as development, test, and production. Traditionally, these scenarios have been difficult to manage to ensure critical applications get the resources they need while managing less critical resources to ensure they do not over consume.
Host I/O limits, like Quality of Service (QoS), provide an excellent means to manage these types of workloads. Instead of trying to manage workloads with multiple storage pools, use host I/O limits. Host I/O limits allow LUNs to be restricted to a specified amount of IOPS or bandwidth, so they do not adversely impact other applications. Host I/O limits allow storage administrators to ensure applications and environments adhere to budgeted limits which greatly simplify planning and management.
Host I/O limits are recommended for Oracle database environments for several reasons. First, storage administrators can ensure that demanding Oracle databases instances do not overwhelm the entire array by setting limits on database volumes. Also, if the Oracle database is the priority application, they can set limits on other LUNs on the system to ensure that the Oracle database gets the required resources. Another great component of host I/O limits is the ability to burst for a given limit for a specific period, which is user configurable. In this way, small exceptions can still be allowed while maintaining balanced performance.
In development and testing environments, it can be difficult to determine if an application meets performance requirements. Typically, these environments are smaller than production environments and it is not always feasible to keep a copy of production data in these environments due to costs or privacy concerns. An issue with smaller datasets is that the application can run faster and then encounter serious performance issues when deployed on a real dataset in production.
Host I/O limits can be used to restrict the I/O on smaller datasets to highlight I/O-intensive queries. Setting limits on databases in development and testing environments will help identify problem areas so they can be resolved before production deployment. The result is improved Oracle databases service levels and greater scalability.
For additional information, see the Dell Unity: Unisphere Overview document.