6.5.1

Table Of Contents
About Virtual Machine Storage Policies
Virtual machine storage policies are essential to virtual machine provisioning. The policies control which
type of storage is provided for the virtual machine, how the virtual machine is placed within the storage,
and which data services are oered for the virtual machine.
vSphere includes default storage policies. However, you can dene and assign new policies.
You use the VM Storage Policies interface to create a storage policy. When you dene the policy, you specify
various storage requirements for applications that run on virtual machines. You can also use storage policies
to request specic data services, such as caching or replication, for virtual disks.
You apply the storage policy when you create, clone, or migrate the virtual machine. After you apply the
storage policy, the Storage Policy Based Management (SPBM) mechanism places the virtual machine in a
matching datastore and, in certain storage environments, determines how the virtual machine storage
objects are provisioned and allocated within the storage resource to guarantee the required level of service.
The SPBM also enables requested data services for the virtual machine. vCenter Server monitors policy
compliance and sends an alert if the virtual machine is in breach of the assigned storage policy.
See vSphere Storage for more information.
About I/O Filters
I/O lters that are associated with virtual disks gain direct access to the virtual machine I/O path regardless
of the underlying storage topology.
VMware oers certain categories of I/O lters. In addition, the I/O lters can be created by third-party
vendors. Typically, they are distributed as packages that provide an installer to deploy lter components on
vCenter Server and ESXi host clusters.
When I/O lters are deployed on the ESXi cluster, vCenter Server automatically congures and registers an
I/O lter storage provider, also called a VASA provider, for each host in the cluster. The storage providers
communicate with vCenter Server and make data services oered by the I/O lter visible in the VM Storage
Policies interface. You can reference these data services when dening common rules for a VM policy. After
you associate virtual disks with this policy, the I/O lters are enabled on the virtual disks.
See vSphere Storage for more information.
Storage I/O Control Requirements
Storage I/O Control has several requirements and limitations.
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Datastores that are Storage I/O Control-enabled must be managed by a single vCenter Server system.
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Storage I/O Control is supported on Fibre Channel-connected, iSCSI-connected, and NFS-connected
storage. Raw Device Mapping (RDM) is not supported.
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Storage I/O Control does not support datastores with multiple extents.
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Before using Storage I/O Control on datastores that are backed by arrays with automated storage tiering
capabilities, check the VMware Storage/SAN Compatibility Guide to verify whether your automated tiered
storage array has been certied to be compatible with Storage I/O Control.
Automated storage tiering is the ability of an array (or group of arrays) to migrate LUNs/volumes or
parts of LUNs/volumes to dierent types of storage media (SSD, FC, SAS, SATA) based on user-set
policies and current I/O paerns. No special certication is required for arrays that do not have these
automatic migration/tiering features, including those that provide the ability to manually migrate data
between dierent types of storage media.
vSphere Resource Management
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