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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<strong>ESXi</strong> Hosts and Multiple <strong>Storage</strong> Arrays<br />
An <strong>ESXi</strong> host can access storage devices presented from multiple storage arrays, including arrays from different<br />
vendors.<br />
When you use multiple arrays from different vendors, the following considerations apply:<br />
n If your host uses the same <strong>Storage</strong> Array Type Plugin (SATP) for multiple arrays, be careful when you<br />
need to change the default Path Selection Policy (PSP) for that SATP. The change will apply to all arrays.<br />
For information on SATPs and PSPs, see Chapter 20, “Understanding Multipathing and Failover,” on<br />
page 193.<br />
n Some storage arrays make recommendations on queue depth and other settings. Typically, these settings<br />
are configured globally at the <strong>ESXi</strong> host level. Making a change for one array impacts other arrays that<br />
present LUNs to the host. For information on changing queue depth, see the <strong>VMware</strong> knowledge base<br />
article at http://kb.vmware.com/kb/1267.<br />
n Use single-initiator-single-target zoning when zoning <strong>ESXi</strong> hosts to Fibre Channel arrays. With this type<br />
of configuration, fabric related events that occur on one array do not impact other arrays. For more<br />
information about zoning, see “Using Zoning with Fibre Channel SANs,” on page 36.<br />
Making LUN Decisions<br />
You must plan how to set up storage for your <strong>ESXi</strong> systems before you format LUNs with VMFS datastores.<br />
When you make your LUN decision, keep in mind the following considerations:<br />
n Each LUN should have the correct RAID level and storage characteristic for the applications running in<br />
virtual machines that use the LUN.<br />
n Each LUN must contain only one VMFS datastore.<br />
n If multiple virtual machines access the same VMFS, use disk shares to prioritize virtual machines.<br />
You might want fewer, larger LUNs for the following reasons:<br />
n More flexibility to create virtual machines without asking the storage administrator for more space.<br />
n More flexibility for resizing virtual disks, doing snapshots, and so on.<br />
n Fewer VMFS datastores to manage.<br />
You might want more, smaller LUNs for the following reasons:<br />
n Less wasted storage space.<br />
n Different applications might need different RAID characteristics.<br />
n More flexibility, as the multipathing policy and disk shares are set per LUN.<br />
n Use of Microsoft Cluster Service requires that each cluster disk resource is in its own LUN.<br />
n Better performance because there is less contention for a single volume.<br />
Chapter 2 Overview of Using <strong>ESXi</strong> with a SAN<br />
When the storage characterization for a virtual machine is not available, there is often no simple method to<br />
determine the number and size of LUNs to provision. You can experiment using either a predictive or adaptive<br />
scheme.<br />
<strong>VMware</strong>, Inc. 29