Queue depth is the number of disk transactions that are in flight between an initiator (HBA port on a Linux server) and a target (port on PowerStore appliance). The initiators are one or more FC or iSCSI ports on the host server which are paired with corresponding target ports of the same protocol type on PowerStore. Any given target port can be paired with multiple initiator ports. To address this issue, the initiator queue depth throttles the number of transactions that any given initiator can send to a target port from a host. This throttling helps to prevent the target ports from becoming flooded. With flooding, transactions are queued which causes higher latency and degraded performance for the affected workloads.
The default queue depth value of 32 may be adequate for Elastic Stack, but other values may work too. These values should be determined as directed in the section Elastic Stack sizing.
