This chart displays the normalized latency in microseconds on the datastore, which is the latency that is monitored by Storage I/O Control to detect congestion on the datastore. This metric computes a weighted response time across all hosts and VMs accessing the datastore. I/O count is used as the weight for the response time. It captures the device level latency and does not include any queuing inside the hypervisor storage stack or inside the VM. It is adjusted for I/O size, meaning that high latencies that are the result of very large I/Os are discounted so as not to make the datastore seem slower than it really is. Data for all virtual machines is combined. This chart will display zero values when Storage I/O Control is disabled.

This chart is located in the Performance view of the datastore Performance tab. The sizeNormalizedDatastoreLatency counter can also be displayed for datastore cluster charts.

Table 1. Data Counters

Chart Label

Description

Storage I/O Control Normalized Latency

This is the latency that is monitored by Storage I/O Control to detect congestion on the datastore.

  • Counter: sizeNormalizedDatastoreLatency

  • Stats Type: Absolute

  • Unit: Microseconds

  • Rollup Type: Average

  • Collection Level: 3