3PAR AIX Implementation Guide (320-200187, June 2011)

2.10
Setting Up and Zoning the Fabric
3PAR AIX 5.3, 6.1, and 7.1 Implementation Guide
3PAR Confidential
2.4.2 Target Port Limitations and Specifications
In order to avoid the overwhelming of a target port and ensure continuous I/O operations,
refer to the following limitations on a target port:
■ Maximum of 64 host server ports per InServ Storage Server port, with a maximum total of
1,024 host server ports per InServ Storage Server.
■ I/O queue depth on each InServ Storage Server HBA model as follows:
◆ QLogic 2G: 497
◆ LSI 2G: 510
◆ Emulex 4G: 959
◆ 3PAR HBA 4G: 1638
■ The I/O queues are shared amongst the connected host server HBA ports on a first-come,
first-served basis.
■ When all queues are in use and a host HBA port tries to initiate I/O, it will receive a target
queue full response from the InServ Storage Server port. This can result in erratic I/O
performance on each host server. If this condition occurs, each host server should be
throttled so that they cannot overrun the InServ Storage Server port's queues when all host
servers are delivering their maximum number of I/O requests.
NOTE: When host server ports can access multiple targets on fabric zones, the
assigned target number (which is assigned by the host driver) for each discovered
target can change when the host server is booted and some targets are not
present in the zone. This may change the device node access point for devices
during a host server reboot. This issue can occur with any fabric-connected
storage, and is not specific to the InServ Storage Server.