Target Port Limits and Specifications
To avoid overwhelming a target port and ensure continuous I/O operations, observe the following limitations on a target port:
•I/O queue depth on each HP 3PAR StoreServ Storage HBA model, as follows:
◦QLogic 1G: 512
◦QLogic 10G: 2048 (HP 3PAR StoreServ 10000 and HP 3PAR StoreServ 7000 systems only)
•The I/O queues are shared among the connected host HBA ports on a
•When all queues are in use and a host HBA port tries to initiate I/O, it receives a target queue full response from the HP 3PAR StoreServ Storage port. This condition can result in erratic I/O performance on each host. If this condition occurs, each host should be throttled so that it cannot overrun the HP 3PAR StoreServ Storage port's queues when all hosts are delivering their maximum number of I/O requests.
HP 3PAR Priority Optimization
The HP 3PAR Priority Optimization feature introduced in HP 3PAR OS versions 3.1.2.MU2 is a more efficient and dynamic solution for managing server workloads and can be utilized as an alternative to setting host I/O throttles. Using this feature, a storage administrator is able to share storage resources more effectively by enforcing quality of service limits on the array. No special settings are needed on the host side to obtain the benefit of Priority Optimization although certain per target or per adapter throttle settings may need to be adjusted in rare cases. For complete details of how to use Priority Optimization (Quality of Service) on HP 3PAR arrays, please read the HP 3PAR Priority Optimization technical white paper available at http://www.hp.com/go/ bsc.
