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

Managing Storage Devices 15Manage local and networked storage device that your ESXi host has access to.This chapter includes the following topics:• “Understanding Storage Device Naming,” on page 121• “Storage Refresh and Rescan Operations,” on page 123• “Identifying Device Connectivity Problems,” on page 124Understanding Storage Device NamingEach storage device, or LUN, is identified by several names.Device IdentifiersDepending on the type of storage, the ESXi host uses different algorithms and conventions to generate anidentifier for each storage device.SCSI INQUIRYidentifiers.The host uses the SCSI INQUIRY command to query a storage device anduses the resulting data, in particular the Page 83 information, to generate aunique identifier. Device identifiers that are based on Page 83 are uniqueacross all hosts, persistent, and have one of the following formats:• naa.number• t10.number• eui.numberThese formats follow the T10 committee standards. See the SCSI-3documentation on the T10 committee Web site.Path-based identifier.When the device does not provide the Page 83 information, the hostgenerates an mpx.path name, where path represents the first path to thedevice, for example, mpx.vmhba1:C0:T1:L3. This identifier can be used in thesame way as the SCSI INQUIRY identifies.The mpx. identifier is created for local devices on the assumption that theirpath names are unique. However, this identifier is neither unique norpersistent and could change after every boot.Typically, the path to the device has the following format:VMware, Inc. 121