vsphere-esxi-vcenter-server-55-storage-guide

Best Practices for iSCSI Storage 14When using ESXi with the iSCSI SAN, follow best practices that VMware offers to avoid problems.Check with your storage representative if your storage system supports Storage API - Array Integrationhardware acceleration features. If it does, refer to your vendor documentation for information on how toenable hardware acceleration support on the storage system side. For more information, see Chapter 24,“Storage Hardware Acceleration,” on page 235.This chapter includes the following topics:• “Preventing iSCSI SAN Problems,” on page 115• “Optimizing iSCSI SAN Storage Performance,” on page 116• “Checking Ethernet Switch Statistics,” on page 119• “iSCSI SAN Configuration Checklist,” on page 119Preventing iSCSI SAN ProblemsWhen using ESXi in conjunction with a SAN, you must follow specific guidelines to avoid SAN problems.You should observe these tips for avoiding problems with your SAN configuration:• Place only one VMFS datastore on each LUN. Multiple VMFS datastores on one LUN is notrecommended.• Do not change the path policy the system sets for you unless you understand the implications ofmaking such a change.• Document everything. Include information about configuration, access control, storage, switch, serverand iSCSI HBA configuration, software and firmware versions, and storage cable plan.• Plan for failure:• Make several copies of your topology maps. For each element, consider what happens to your SANif the element fails.• Cross off different links, switches, HBAs and other elements to ensure you did not miss a criticalfailure point in your design.• Ensure that the iSCSI HBAs are installed in the correct slots in the ESXi host, based on slot and busspeed. Balance PCI bus load among the available busses in the server.• Become familiar with the various monitor points in your storage network, at all visibility points,including ESXi performance charts, Ethernet switch statistics, and storage performance statistics.• Be cautious when changing IDs of the LUNs that have VMFS datastores being used by your host. If youchange the ID, virtual machines running on the VMFS datastore will fail.VMware, Inc. 115