vSphere Storage - ESXi 5.1 - Documentation - VMware
vSphere Storage - ESXi 5.1 - Documentation - VMware
vSphere Storage - ESXi 5.1 - Documentation - VMware
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n Scalability improvements on storage devices that support hardware acceleration. For information, see<br />
Chapter 21, “<strong>Storage</strong> Hardware Acceleration,” on page 215.<br />
n Default use of hardware assisted locking, also called atomic test and set (ATS) locking, on storage devices<br />
that support hardware acceleration. For information about how to turn off ATS locking, see “Turn off ATS<br />
Locking,” on page 157.<br />
n Ability to reclaim physical storage space on thin provisioned storage devices. For information, see “Array<br />
Thin Provisioning and VMFS Datastores,” on page 230.<br />
n Online upgrade process that upgrades existing datastores without disrupting hosts or virtual machines<br />
that are currently running. For information, see “Upgrading VMFS Datastores,” on page 165.<br />
For information about block size limitations of a VMFS datastore, see the <strong>VMware</strong> knowledge base article at<br />
http://kb.vmware.com/kb/1003565.<br />
VMFS Datastores and <strong>Storage</strong> Disk Formats<br />
<strong>Storage</strong> devices that your host supports can use either the master boot record (MBR) format or the GUID<br />
partition table (GPT) format.<br />
With <strong>ESXi</strong> 5.0 and later, if you create a new VMFS5 datastore, the device is formatted with GPT. The GPT<br />
format enables you to create datastores larger than 2TB and up to 64TB for a single extent.<br />
VMFS3 datastores continue to use the MBR format for their storage devices. Consider the following items when<br />
you work with VMFS3 datastores:<br />
n For VMFS3 datastores, the 2TB limit still applies, even when the storage device has a capacity of more<br />
than 2TB. To be able to use the entire storage space, upgrade a VMFS3 datastore to VMFS5. Conversion<br />
of the MBR format to GPT happens only after you expand the datastore to a size larger than 2TB.<br />
n When you upgrade a VMFS3 datastore to VMFS5, the datastore uses the MBR format. Conversion to GPT<br />
happens only after you expand the datastore to a size larger than 2TB.<br />
n When you upgrade a VMFS3 datastore, remove from the storage device any partitions that <strong>ESXi</strong> does not<br />
recognize, for example, partitions that use the EXT2 or EXT3 formats. Otherwise, the host cannot format<br />
the device with GPT and the upgrade fails.<br />
n You cannot expand a VMFS3 datastore on devices that have the GPT partition format.<br />
VMFS Datastores as Repositories<br />
<strong>ESXi</strong> can format SCSI-based storage devices as VMFS datastores. VMFS datastores primarily serve as<br />
repositories for virtual machines.<br />
With VMFS5, you can have up to 256 VMFS datastores per host, with the maximum size of 64TB. The required<br />
minimum size for a VMFS datastore is 1.3GB, however, the recommended minimum size is 2GB.<br />
NOTE Always have only one VMFS datastore for each LUN.<br />
Chapter 17 Working with Datastores<br />
You can store multiple virtual machines on the same VMFS datastore. Each virtual machine, encapsulated in<br />
a set of files, occupies a separate single directory. For the operating system inside the virtual machine, VMFS<br />
preserves the internal file system semantics, which ensures correct application behavior and data integrity for<br />
applications running in virtual machines.<br />
When you run multiple virtual machines, VMFS provides specific locking mechanisms for virtual machine<br />
files, so that virtual machines can operate safely in a SAN environment where multiple <strong>ESXi</strong> hosts share the<br />
same VMFS datastore.<br />
In addition to virtual machines, the VMFS datastores can store other files, such as virtual machine templates<br />
and ISO images.<br />
<strong>VMware</strong>, Inc. 155