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

vSphere StorageFigure 6‐1. SAN FailoverHost 1 Host 2HBA1HBA2HBA3HBA4FC switch 1FC switch 2SP1SP2storageThis configuration provides two paths from each HBA, so that each element of the connection can fail overto a redundant path. The order of the paths in this configuration provides HBA and switch failover withoutthe need to trigger SP failover. The storage processor that the preferred paths are connected to must own theLUNs. In the preceding example configuration, SP1 owns them.NOTE The preceding example assumes that the switches are not connected through an Inter-Switch Link(ISL) in one fabric.Disabling Auto Volume TransferTo avoid the possibility of path thrashing, disable Auto Volume Transfer (AVT) on the SAN storageprocessors. If AVT is enabled, the two storage processors can alternately take ownership of the LUN incertain situations, resulting in performance degradation. AVT is also known as ADT (Auto Disk Transfer).To disable AVT, in the DS 4800 Storage Manager, for each port defined in each host group that containsHBAs for one or more ESXi hosts, set the host type to LNXCL or, in later versions, to VMware.You must reboot the hosts after you change the AVT configuration.Configure Storage Processor Sense DataA DS4800 SP that runs Windows as a guest operating system should return Not Ready sense data when it isquiescent. Returning Unit Attention might cause the Windows guest to fail during a failover.Procedure1 Determine the index for the LNXCL host type by using the following commands in a shell window.Press Enter after each command.SMcli.exe ip-addr-for-SPA show hosttopology; Enter SMcli.exe ip-addr-for-SPB showhosttopologyThe following commands assume that 13 is the index corresponding to LNXCL in the NVSRAM host typedefinitions. If your storage processors have LNXCL at a different index, substitute that index for 13 in thefollowing commands.2 Execute these commands for SPA to have it return Not Ready sense data.Press Enter only after you enter all commands.SMcli.exe ip-addr-for-SPAset controller [a] HostNVSRAMBYTE [13,0x12]=0x01; set controller [a] HostNVSRAMBYTE[13,0x13]=0x00; reset Controller [a]52 VMware, Inc.