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| Changing the Tier 0 storage latency QoS parameter from the command line | ||
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| Prev | Ensuring predictable performance | Next |
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| Changing the Tier 0 storage latency QoS parameter from the command line | ||
|---|---|---|
| Prev | Ensuring predictable performance | Next |
HyperScale provides the hyperscale qos-config-update command to modify the Tier 0 storage (SSD storage) latency value in order to achieve the desired storage performance levels at the compute plane. This command sets the value for the qos_config_ssd parameter that defines the worst case latency associated with the Tier 0 storage layer.
A higher latency value can ensure higher IOPS from the compute node but does not guarantee a high QoS miniops. A lower latency value guarantees high QoS miniops but provides lower overall IOPS.
To modify the Tier 0 storage latency, run the following command on the HyperScale controller or data node:
# hyperscale qos-config-update --hostname <computenodename> \
--latency <latencyinmicroseconds>
Here,
<computenodename> is the Fully Qualified Host Name (FQHN) of the compute node for which the QoS configuration is to be updated.
This parameter is optional. If not specified, the command applies to all the compute nodes in the HyperScale configuration.
<latencyinmicroseconds> is the worst case latency for Tier 0 storage (SSD storage) and is defined in microseconds. This parameter can take a minimum value of 1000 microseconds and a maximum value of 10,000 microseconds.
This command updates the in-memory latency value as well as the value that is stored in the QoS configuration file. The updated value takes effect immediately.
When you run this command the command output confirms whether or not the command was successful. For example, when you run the following command to change the latency to 1500 microseconds:
# hyperscale qos-config-update --latency 1500
The following output confirms that the command was successful:
+----------+---------------------------------------------------+ | Property | Value | +----------+---------------------------------------------------+ | response | Specified qos configuration updated successfully. | +----------+---------------------------------------------------+
In cases where the command fails for some reason, the output confirms the failure and also displays the reason for the failure.
For example, when you run the following command to change the latency to 1500 on a non-existent compute node named computenodea.bc.xyz.com:
# hyperscale qos-config-update --hostname computenodea.bc.xyz.com --latency 1500
The following output confirms that the command failed due to an invalid host name:
+----------+---------------------------+ | Property | Value | +----------+---------------------------+ | response | Invalid hostname provided | +----------+---------------------------+