Managing throttles for host clusters

You can create, modify, and remove throttles for host clusters by using the management GUI or the command-line interface.

Throttles are mechanisms to control the amount of resources that are used when the system is processing I/Os on a specific host or host cluster. If a throttle is defined, the system either processes the I/O, or delays the processing on the I/O to free resources for more critical I/O.

Using the management GUI

If you are creating a new throttle for a host cluster, any hosts within that cluster adopt the throttle for processing. If hosts that are being added to the host cluster have throttles defined, the throttles must be removed. Ensure that any throttles on hosts that are members of the host cluster are removed before you create a new throttle. To create a new throttle for a host cluster, complete these steps:
  1. In the management GUI, select Hosts > Host Clusters.
  2. Right-click a host cluster and select Edit Throttle....
  3. On the Edit Throttle page, enter values for the following throttles:
    Bandwidth Limit
    Enter the maximum amount of bandwidth the host can process before the system delays processing for this host. Click Create.
    IOPS Limit
    Enter the maximum I/O operations per second the host can process before the system delays processing for this host. Click Create.
To change an existing throttle, complete the following steps:
  1. In the management GUI, select Hosts > Host Clusters.
  2. Right-click a host cluster and select Edit Throttle....
  3. On the Edit Throttle page, enter values for the following throttles:
    Bandwidth Limit
    Enter the maximum amount of bandwidth the host can process before the system delays processing for this host. Click Save.
    IOPS Limit
    Enter the maximum I/O operations per second the host can process before the system delays processing for this host. Click Save.
To remove throttles for a host cluster, complete these steps:
  1. In the management GUI, select Hosts > Host Clusters.
  2. Right-click a host cluster and select Edit Throttle....
  3. On the Edit Throttle page, click Remove by the throttle that you want to delete. All hosts in the host cluster no longer use that throttle.

Using the command-line interface

To create a new throttle for bandwidth and IOPS for a host cluster with the command-line interface, enter the following command:
mkthrottle -type hostcluster -bandwidth bandwidth_limit_in_mb -iops iops_limit -hostcluster  hostcluster_id_or_hostcluster_name
where bandwidth_limit_in_mb is the maximum amount of bandwidth that the system can process for the specified host cluster before the system delays processing of I/O for that host cluster. The iops_limit is the maximum I/O operations per second that the system can process before the system delays processing for this host cluster. These settings apply to all hosts within the host cluster. Throttle limits are applied to all hosts in host cluster. After the configured limit is reached, additional delay is introduced to I/Os from all member hosts in host cluster. The hostcluster_id_or_hostcluster_name is the ID or name of the host cluster that the throttle applies to.
To change an existing throttle for bandwidth and IOPS for a host cluster with the command-line interface, enter the following command:
chthrottle -type hostcluster -bandwidth bandwidth_limit_in_mb -iops iops_limit throttle_name_or_id
where bandwidth_limit_in_mb is the maximum amount of bandwidth that the system can process for the specified host cluster before the system delays processing of I/O for that host cluster. The iops_limit is the maximum I/O operations per second that the system can process before the system delays processing for this host cluster. These settings apply to all hosts within the host cluster. Throttle limits are applied to all hosts in host cluster. After the configured limit is reached, additional delay is introduced to I/Os from all member hosts in host cluster. The throttle_name_or_id is the ID or name of the throttle that is being changed.
To remove a throttle for host cluster with the command-line interface, enter the following command:
rmthrottle throttle_name_or_id
where throttle_name_or_id is the ID or name of the throttle that is being removed.