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# Set host I/O limits

Host I/O limits (quotas) can be used to limit the amount of Front End (FE) Bandwidth and I/O operations per second (IOPS) that can be consumed by a set of storage volumes over a set of director ports.

## About this task

The bandwidth and IOPS against the set of volumes over the set of director ports that the storage system monitors to ensure that they do not exceed the user specified maximum bandwidth or maximum IOPS. This feature enables you to place limits on the FE Bandwidth and IOPS consumed by applications on the storage system.

Host I/O limits are defined as storage group attributes – the maximum bandwidth (in MB per second) and the maximum IOPS . For a cascaded storage group, a host I/O limit can be added for the parent and the child storage group. If set for both, the child limits cannot exceed that of the parent.

The Host I/O limit for a storage group can be either active or inactive, only the active Host I/O limit can limit the FE bandwidth and IOPS of the volumes in a storage group. The Host I/O limit becomes active when a provisioning view is created using the storage group and becomes inactive when the view is deleted. When a view is created on a parent storage group with a Host I/O limit, the limit is shared among all the volumes in all child storage groups.

The Host I/O limit of the storage group applies to all the director ports of the port group in the provisioning view. The Host I/O limit is divided equally among all the directors in the port group independent of the number of ports on each director. For this reason, Dell Technologies recommends that you configure only one of the ports of a director in the port group.

Before you begin:

- The maximum number of quotas per storage system is 16,000.
- For more information about setting host I/O limits, see the Solutions Enabler Array Management CLI Product Guide.

To set host I/O limits:

## Steps

1. Select a storage system.
2. Select Storage > Storage Groups, and then select the storage group and select Set Host I/O Limits.
3. Select and type values for one or both of the following:
   - MB/Sec—Maximum bandwidth (in MB per second) - valid values range from 1 MB/sec to 100,000 MB/sec.
   - IO/Sec—Maximum I/O per second - valid values range from 100 I/O per second to 2,000,000 I/O per second, in 100 increments of 100.
4. To configure a dynamic distribution of host I/O limits, set Dynamic Distribution to one of the following; otherwise, leave this field set to Never (default).
   - Always—Enables full dynamic distribution mode. When enabled, the configured host I/O limits are dynamically distributed across the configured ports, thus enabling the limits on each individual port to adjust to fluctuating demand.
   - OnFailure—Enables port failure capability. When enabled, the fraction of configured host I/O limits available to a configured port adjusts based on the number of ports online.
5. Click OK.