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Does defragmentation of FC-connected virtual disks improve performance?

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Applies to

  • ONTAP 9
  • Fibre Channel (FC) 
  • Virtual disks (VMDK)
  • Logical Unit Numbers (LUNs)
  • Windows operating systems with NTFS file systems

Answer

No, defragmentation of virtual disks (such as VMDK) or LUNs does not improve performance on the storage side.
Here’s why:
  • Block Management: Storage systems manage data at the block level. Even if files appear contiguous on the Windows file system (e.g., NTFS), the underlying storage may still have blocks scattered across different physical locations.
  • Defragmentation Impact: Running defragmentation on Windows only reorganizes the file system's view of the data. It does not change the physical block arrangement on the storage system.
  • Performance Considerations: Defragmentation can increase I/O load temporarily, potentially leading to a short-term performance decrease rather than an improvement.

Additional Information

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