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

vSphere Storage• Become familiar with the various monitor points in your storage network, at all visibility points,including host's performance charts, FC switch statistics, and storage performance statistics.• Be cautious when changing IDs of the LUNs that have VMFS datastores being used by your ESXi host.If you change the ID, the datastore becomes inactive and its virtual machines fail. You can resignaturethe datastore to make it active again. See “Managing Duplicate VMFS Datastores,” on page 141.If there are no running virtual machines on the VMFS datastore, after you change the ID of the LUN,you must use rescan to reset the ID on your host. For information on using rescan, see “Storage Refreshand Rescan Operations,” on page 123.Disable Automatic Host Registration in the vSphere Web ClientWhen you use EMC CLARiiON or Invista arrays for storage, it is required that the hosts register with thearrays. ESXi performs automatic host registration by sending the host's name and IP address to the array. Ifyou prefer to perform manual registration using storage management software, disable the ESXi autoregistrationfeature.Procedure1 Browse to the host in the vSphere Web Client navigator.2 Click the Manage tab, and click Settings.3 Under System, click Advanced System Settings.4 Under Advanced System Settings, select the Disk.EnableNaviReg parameter and click the Edit icon.5 Change the value to 0.This disables the automatic host registration enabled by default.Optimizing Fibre Channel SAN Storage PerformanceSeveral factors contribute to optimizing a typical SAN environment.If the environment is properly configured, the SAN fabric components (particularly the SAN switches) areonly minor contributors because of their low latencies relative to servers and storage arrays. Make sure thatthe paths through the switch fabric are not saturated, that is, that the switch fabric is running at the highestthroughput.Storage Array PerformanceStorage array performance is one of the major factors contributing to the performance of the entire SANenvironment.If there are issues with storage array performance, be sure to consult your storage array vendor’sdocumentation for any relevant information.Follow these general guidelines to improve the array performance in the vSphere environment:• When assigning LUNs, remember that each LUN is accessed by a number of hosts, and that a numberof virtual machines can run on each host. One LUN used by a host can service I/O from many differentapplications running on different operating systems. Because of this diverse workload, the RAID groupcontaining the ESXi LUNs should not include LUNs used by other servers that are not running ESXi.• Make sure read/write caching is enabled.• SAN storage arrays require continual redesign and tuning to ensure that I/O is load balanced across allstorage array paths. To meet this requirement, distribute the paths to the LUNs among all the SPs toprovide optimal load balancing. Close monitoring indicates when it is necessary to rebalance the LUNdistribution.66 VMware, Inc.