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Slow ESX/ESXi performance caused by misconfigured local storage or SAN array (1006602)

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Slow performance can be caused by misconfigured local storage or SAN array.
This article provides steps to determine if the storage for your ESX/ESXi host is properly configured.


For local storage, determine if the host has write-back cache installed. Contact the OEM for model-specific details regarding write-back cache.

If write-back cache is installed in the host, ensure these points are true:

  • The write-back cache is enabled
  • The cache has a battery module installed
  • The battery module is not faulty or otherwise in need of replacement

    Note: Contact you vendor for specific information related to performing these tasks.
For Fibre-channel-based SAN storage, ensure end-to-end speeds are consistent. Consult your SAN and SAN switch documentation for model-specific details regarding setting fibre-channel speeds.
  • Performance problems can arise when the speed differs from the SAN to the HBA. Ensure that the SAN is connected to the SAN switch at the same speed that the SAN switch is connected to the ESX/ESXi HBA.
  • If SAN performance problems persist, set all devices connected through a given SAN switch to use the same speed, as a troubleshooting measure.

    Note: Contact your vendor for more information related to performing these tasks.

Additional Information

For more information on troubleshooting slow template deployment, see Diagnosing slow deployment of templates or clones from vCenter Server (1004002).

See Also

Update History

02/24/2011 - Updated to reflect version 4.x. 06/22/2012 - Updated for 5.x

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  • 16 Ratings