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Table Of Contents
To improve the array performance in the vSphere environment, follow these general guidelines:
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When assigning LUNs, remember that several hosts might access the LUN, and that several virtual
machines can run on each host. One LUN used by a host can service I/O from many different
applications running on different operating systems. Because of this diverse workload, the RAID
group containing the ESXi LUNs typically does not include LUNs used by other servers that are not
running ESXi.
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Make sure that the read/write caching is available.
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SAN storage arrays require continual redesign and tuning to ensure that I/O is load-balanced across
all storage array paths. To meet this requirement, distribute the paths to the LUNs among all the SPs
to provide optimal load-balancing. Close monitoring indicates when it is necessary to rebalance the
LUN distribution.
Tuning statically balanced storage arrays is a matter of monitoring the specific performance statistics,
such as I/O operations per second, blocks per second, and response time. Distributing the LUN
workload to spread the workload across all the SPs is also important.
Note Dynamic load-balancing is not currently supported with ESXi.
Server Performance with Fibre Channel
You must consider several factors to ensure optimal server performance.
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 array.
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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Ensure that each host has enough HBAs to increase throughput for the applications on the host for
the peak period. I/O spread across multiple HBAs provides faster throughput and less latency for
each application.
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To provide redundancy for a potential HBA failure, make sure that the host is connected to a dual
redundant fabric.
vSphere Storage
VMware, Inc. 65