6.5.1

Each server application must have access to its designated storage with the following conditions:
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High I/O rate (number of I/O operations per second)
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High throughput (megabytes per second)
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Minimal latency (response times)
Because each application has different requirements, you can meet these goals by selecting an
appropriate RAID group on the storage system.
To achieve performance goals, follow these guidelines:
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Place each LUN on a RAID group that provides the necessary performance levels. Monitor the
activities and resource use of other LUNS in the assigned RAID group. A high-performance RAID
group that has too many applications doing I/O to it might not meet performance goals required by an
application running on the ESXi host.
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To achieve maximum throughput for all the applications on the host during the peak period, install
enough network adapters or iSCSI hardware adapters. I/O spread across multiple ports provides
faster throughput and less latency for each application.
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To provide redundancy for software iSCSI, make sure that the initiator is connected to all network
adapters used for iSCSI connectivity.
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When allocating LUNs or RAID groups for ESXi systems, remember that multiple operating systems
use and share that resource. The LUN performance required by the ESXi host might be much higher
than when you use regular physical machines. For example, if you expect to run four I/O intensive
applications, allocate four times the performance capacity for the ESXi LUNs.
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When you use multiple ESXi systems with vCenter Server, the storage performance requirements
increase.
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The number of outstanding I/Os needed by applications running on an ESXi system must match the
number of I/Os the SAN can handle.
Network Performance
A typical SAN consists of a collection of computers connected to a collection of storage systems through
a network of switches. Several computers often access the same storage.
The following graphic shows several computer systems connected to a storage system through an
Ethernet switch. In this configuration, each system is connected through a single Ethernet link to the
switch. The switch is connected to the storage system through a single Ethernet link.
vSphere Storage
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