• Slow performance when copying files between Shared VMFS Storage (fibre-channel SAN) and local VMFS storage
• Slow deployment of virtual machines from templates using vCenter Server
  

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.

• 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.