Managing Performance Service Levels

11/25/2022 Contributors

A Performance Service Level enables you to define the performance and storage objectives for a workload. You can assign a Performance Service Level to a workload when initially creating the workload, or afterwards by editing the workload.

The management and monitoring of storage resources are based on Service Level Objectives (SLOs). SLOs are defined by service level agreements that are based on performance and capacity. In Unified Manager, SLOs refer to the Performance Service Level definitions of the applications that are running on NetApp storage. Storage services are differentiated based on the performance and utilization of the underlying resources. A Performance Service Level is a description of the storage service objectives. A Performance Service Level enables the storage provider to specify the performance and capacity objectives for the workload.

Unified Manager provides a few predefined (or canned) Performance Service Levels: Extreme Performance, Performance, and Value. The Extreme Performance, Performance, and Value Performance Service Levels are applicable for most of the common storage workloads in a data center. Unified Manager also offers three Performance Service Levels for database applications: Extreme for Database Logs, Extreme for Database Shared Data, and Extreme for Database Data. These are extremely high-performance Performance Service Levels that support bursty IOPS and are appropriate for database applications with the highest throughput demand. If these predefined Performance Service Levels do not meet your requirements, then you can create new Performance Service Levels based on the definition of the predefined Performance Service Levels.

You can access the Performance Service Levels from the Policies > Performance Service Levels page and by using the storage provider APIs. Managing storage workloads by assigning Performance Service Levels to them is convenient as you do not have to individually manage the storage workloads. Any modifications can also be managed by reassigning another Performance Service Level rather than managing them individually.

You cannot modify a Performance Service Level that is system-defined or that is currently assigned to a workload. You cannot delete a PSL that is assigned to a workload, or if it is the only available Performance Service Level.

The Performance Service Levels page lists the available Performance Service Level policies and enables you to add, edit, and delete them. This page displays the following information:

Field	Description
Name	Name of the Performance Service Level.
Type	Whether the policy is system-defined or user-defined.
Expected IOPS	Minimum number of IOPS that an application is expected to perform on a LUN or file share. Expected IOPS specifies the minimum expected IOPS allocated, based on the storage object allocated size.
Peak IOPS	Maximum number of IOPS that an application can perform on a LUN or file share. Peak IOPS specifies the maximum possible IOPS allocated, based on the storage object allocated size or the storage object used size. Peak IOPS are based on an allocation policy. The allocation policy is either allocated-space or used-space. When the allocation policy is set to allocated-space, the peak IOPS is calculated based on the size of the storage object. When the allocation policy is set to used-space, the peak IOPS is calculated based on the amount of data stored in the storage object, taking into account storage efficiencies. By default, the allocation policy is set to used-space.
Absolute minimum IOPS	The absolute minimum IOPS, which is used as an override when the expected IOPS is less than this value. The value can be between 400 and 1000. The range of absolute minimum IOPS is calculated as follows: Minimum value = 1000/ expected latency The default values of the system-defined Performance Service Levels are computed as the following: Extreme Performance: If expected IOPS >= 6144/TB, then absolute minimum IOPS = 1000 Performance: If expected IOPS >= 2048/TB and < 6144/TB, then absolute minimum IOPS = 500 Value: If expected IOPS >= 128/TB and < 2048/TB, then absolute minimum IOPS = 75 The default values of the system-defined database Performance Service Levels are computed as the following: Extreme for Database Logs: If expected IOPS >= 22528, then absolute minimum IOPS = 4000 Extreme for Database Shared Data: If expected IOPS >= 16384, then absolute minimum IOPS = 2000 Extreme for Database Data: If expected IOPS >= 12288, then absolute minimum IOPS = 2000
Expected latency	Expected latency for storage IOPS in milliseconds per operation (ms/op).
Capacity	Total available and used capacity in the clusters.
Workloads	Number of storage workloads that have been assigned the Performance Service Level.

Field

Description

Name

Name of the Performance Service Level.

Type

Whether the policy is system-defined or user-defined.

Expected IOPS

Minimum number of IOPS that an application is expected to perform on a LUN or file share. Expected IOPS specifies the minimum expected IOPS allocated, based on the storage object allocated size.

Peak IOPS

Maximum number of IOPS that an application can perform on a LUN or file share. Peak IOPS specifies the maximum possible IOPS allocated, based on the storage object allocated size or the storage object used size.

Peak IOPS are based on an allocation policy. The allocation policy is either allocated-space or used-space. When the allocation policy is set to allocated-space, the peak IOPS is calculated based on the size of the storage object. When the allocation policy is set to used-space, the peak IOPS is calculated based on the amount of data stored in the storage object, taking into account storage efficiencies. By default, the allocation policy is set to used-space.

Absolute minimum IOPS

The absolute minimum IOPS, which is used as an override when the expected IOPS is less than this value. The value can be between 400 and 1000. The range of absolute minimum IOPS is calculated as follows:

Minimum value = 1000/ expected latency

The default values of the system-defined Performance Service Levels are computed as the following:

Extreme Performance: If expected IOPS >= 6144/TB, then absolute minimum IOPS = 1000
Performance: If expected IOPS >= 2048/TB and < 6144/TB, then absolute minimum IOPS = 500
Value: If expected IOPS >= 128/TB and < 2048/TB, then absolute minimum IOPS = 75

The default values of the system-defined database Performance Service Levels are computed as the following:

Extreme for Database Logs: If expected IOPS >= 22528, then absolute minimum IOPS = 4000
Extreme for Database Shared Data: If expected IOPS >= 16384, then absolute minimum IOPS = 2000
Extreme for Database Data: If expected IOPS >= 12288, then absolute minimum IOPS = 2000

Expected latency

Expected latency for storage IOPS in milliseconds per operation (ms/op).

Capacity

Total available and used capacity in the clusters.

Workloads

Number of storage workloads that have been assigned the Performance Service Level.

Note that if workloads exceed the expected latency value for 30% of the time during the previous hour that Unified Manager will generate one of the following events to notify you of a potential performance issue: “Workload Volume Latency Threshold Breached as defined by Performance Service Level Policy” or “Workload LUN Latency Threshold Breached as defined by Performance Service Level Policy”.

The following table provides information about the system-defined Performance Service Levels:

Performance Service Level	Description and use case	Expected latency (ms/op)	Peak IOPS	Expected IOPS	Absolute minimum IOPS
Extreme Performance	Provides extremely high throughput at a very low latency Ideal for latency-sensitive applications	1	12288	6144	1000
Performance	Provides high throughput at a low latency Ideal for database and virtualized applications	2	4096	2048	500
Value	Provides high storage capacity and moderate latency Ideal for high-capacity applications such as email, web content, file shares, and backup targets	17	512	128	75
Extreme for Database Logs	Provides maximum throughput at the lowest latency. Ideal for database applications supporting database logs. This PSL provides the highest throughput because database logs are extremely bursty and logging is constantly in demand.	1	45056	22528	4000
Extreme for Database Shared Data	Provides very high throughput at the lowest latency. Ideal for database applications data that is stored in a common data store, but is shared across databases.	1	32768	16384	2000
Extreme for Database Data	Provides high throughput at the lowest latency. Ideal for database applications data, such as database table information and metadata.	1	24576	12288	2000

Guidelines for creating a custom Performance Service Level

If the existing Performance Service Levels do not meet the Service Level Objective (SLO) requirements for your storage workloads, you can create a custom Performance Service Level. However, it is recommended that you attempt to use the system-defined Performance Service Levels for your storage workloads, and only create custom Performance Service Levels if necessary.

Managing Performance Service Levels

Creating your file...

Guidelines for creating a custom Performance Service Level