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

vSphere StorageVMware tests ESXi with storage systems in the following configurations:Basic ConnectivityiSCSI FailoverStorage Port FailoverBooting from a SANTests whether ESXi can recognize and operate with the storage system. Thisconfiguration does not allow for multipathing or any type of failover.The server is equipped with multiple iSCSI HBAs or NICs. The server isrobust to HBA or NIC failure.The server is attached to multiple storage ports and is robust to storage portfailures and switch failures.The host successfully boots from a LUN configured on the iSCSI SAN.General Considerations for iSCSI SAN Storage SystemsWhen you prepare your iSCSI SAN storage system to work with ESXi, you need to follow specific generalrequirements that apply to all storage systems.For all storage systems, the following general requirements exist:• LUNs must be presented to each HBA of each host with the same LUN ID number. If different numbersare used, the ESXi hosts do not recognize different paths to the same LUN. Because instructions on howto configure identical SAN LUN IDs are vendor-specific, consult your storage documentation for moreinformation.• Unless specified for individual storage systems discussed in this chapter, set the host type for LUNspresented to ESXi to Linux or Linux Cluster, if applicable to your storage system. The method ESXiuses to access the storage system is most compatible with Linux access, however, this can varydepending on the storage system you are using.• If you are using vMotion, DRS, or HA, make sure that source and target hosts for virtual machines cansee the same LUNs with identical LUN IDs. SAN administrators might find it counterintuitive to havemultiple hosts see the same LUNs because they might be concerned about data corruption. However,VMFS prevents multiple virtual machines from writing to the same file at the same time, soprovisioning the LUNs to all required ESXi system is appropriate.• If you do not have CHAP authentication set up on the LUNs that are being accessed, you must alsodisable CHAP on the ESXi host. Otherwise, authentication of the storage system fails, although theLUNs have no CHAP requirement.EMC CLARiiON Storage SystemsEMC CLARiiON storage systems work with ESXi hosts in iSCSI SAN configurations. Generally, you use theEMC software to perform configurations.This is an active-passive disk array, so any related issues that apply to all active-passive disk arrays arerelevant. In addition, keep in mind the following:• To avoid the possibility of path thrashing, the default multipathing policy is Most Recently Used, notFixed. The ESXi system sets the default policy when it identifies the storage system.• To boot from a SAN, choose the active storage processor for the boot LUN’s target in the HBA BIOS.• For ESXi to support EMC CLARiiON with ALUA, check the HCLs to make sure that you use the correctfirmware version on the storage array. For additional information, contact your storage vendor.• Certain EMC CLARiiON CX3 models might not behave appropriately during periods of networkcongestion. For information on how to address this behavior, see the VMware knowledge base article athttp://kb.vmware.com/kb/1002598.102 VMware, Inc.