6.0.1

Table Of Contents
Managing Storage I/O Resources 8
vSphere Storage I/O Control allows cluster-wide storage I/O prioritization, which allows better workload
consolidation and helps reduce extra costs associated with over provisioning.
Storage I/O Control extends the constructs of shares and limits to handle storage I/O resources. You can
control the amount of storage I/O that is allocated to virtual machines during periods of I/O congestion,
which ensures that more important virtual machines get preference over less important virtual machines for
I/O resource allocation.
When you enable Storage I/O Control on a datastore, ESXi begins to monitor the device latency that hosts
observe when communicating with that datastore. When device latency exceeds a threshold, the datastore is
considered to be congested and each virtual machine that accesses that datastore is allocated I/O resources
in proportion to their shares. You set shares per virtual machine. You can adjust the number for each based
on need.
Configuring Storage I/O Control is a two-step process:
1 Enable Storage I/O Control for the datastore.
2 Set the number of storage I/O shares and upper limit of I/O operations per second (IOPS) allowed for
each virtual machine.
By default, all virtual machine shares are set to Normal (1000) with unlimited IOPS.
NOTE Storage I/O Control is enabled by default on Storage DRS-enabled datastore clusters.
This chapter includes the following topics:
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“Storage I/O Control Requirements,” on page 49
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“Storage I/O Control Resource Shares and Limits,” on page 50
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“Set Storage I/O Control Resource Shares and Limits,” on page 51
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“Enable Storage I/O Control,” on page 51
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“Set Storage I/O Control Threshold Value,” on page 52
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“Storage DRS Integration with Storage Profiles,” on page 53
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.
VMware, Inc.
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