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How Oracle determines sector size using VPD or OS-level reporting

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san
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Applies to

  • FCP
  • Oracle ASM
  • Solaris

Answer

  • Oracle ASM determines disk sector size based on two sources:
    • Device VPD (Vital Product Data): ASM queries the disk’s VPD page for physical and logical sector size. If available, these values are used for SECTOR_SIZE and LOGICAL_SECTOR_SIZE.
    • OS Device Driver: If VPD is missing or incomplete, ASM falls back to the OS-reported logical block size (on Solaris, from sd.conf or kernel geometry).
  • We do not suspect any storage-side issue since the same LUN is presented to both nodes.
  • The discrepancy appears to be due to how Oracle determines sector size using VPD or OS-level reporting.

Additional Information

  • At disk group creation, ASM sets:
    • SECTOR_SIZE = physical sector size from VPD (or OS if VPD absent)
    • LOGICAL_SECTOR_SIZE = logical sector size from VPD (or OS fallback)
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