6.5

Table Of Contents
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Virtual Flash storage - Use commands in the esxcli storage vflash namespace to manage
VMware vSphere Flash Read Cache.
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Virtual volumes - Virtual volumes oer a dierent layer of abstraction than datastores. As a result,
ner-grained management is possible. Use commands in the esxcli storage vvol namespace.
Datastores
ESXi hosts use storage space on a variety of physical storage systems, including internal and external
devices and networked storage.
A host can discover storage devices to which it has access and format them as datastores. Each datastore is a
special logical container, analogous to a le system on a logical volume, where the host places virtual disk
les and other virtual machine les. Datastores hide specics of each storage product and provide a uniform
model for storing virtual machine les.
Depending on the type of storage you use, datastores can be backed by the following le system formats.
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Virtual Machine File System (VMFS) - High-performance le system optimized for storing virtual
machines. Your host can deploy a VMFS datastore on any SCSI-based local or networked storage
device, including Fibre Channel and iSCSI SAN equipment.
As an alternative to using the VMFS datastore, your virtual machine can have direct access to raw
devices and use a mapping le (RDM) as a proxy. See “Managing the Virtual Machine File System with
vmkfstools,” on page 30.
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Network File System (NFS) - File system on a NAS storage device. ESXi supports NFS version 3 over
TCP/IP. The host can access a designated NFS volume located on an NFS server, mount the volume, and
use it for any storage needs.
Storage Device Naming
Each storage device, or LUN, is identied by several device identier names.
Device Identifiers
Depending on the type of storage, the ESXi host uses dierent algorithms and conventions to generate an
identier for each storage device.
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SCSI INQUIRY identiers - The host uses the SCSI INQUIRY command to query a storage device and
uses the resulting data, in particular the Page 83 information, to generate a unique identier. SCSI
INQUIRY device identiers are unique across all hosts, persistent, and have one of the following
formats.
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naa.<number>
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t10.<number>
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eui.<number>
These formats follow the T10 commiee standards. See the SCSI-3 documentation on the T10 commie
Web site for information on Page 83.
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Path-based identier. If the device does not provide the information on Page 83 of the T10 commiee
SCSI-3 documentation, the host generates an mpx.<path> name, where <path> represents the rst path to
the device, for example, mpx.vmhba1:C0:T1:L3. This identier can be used in the same way as the SCSI
inquiry identiers.
The mpx. identier is created for local devices on the assumption that their path names are unique.
However, this identier is neither unique nor persistent and could change after every boot.
vSphere Command-Line Interface Concepts and Examples
44 VMware, Inc.