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NetApp Knowledge Base

Why does a drive not fail after logging multiple errors?

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disk-drives
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Applies to

NetApp E-Series and EF-Series

Answer

Drives can be failed for different reasons.

  • Drives will always be failed upon failing a write request.
  • Other failure reasons are determined by the Drive Error Thresholds specified for each drive type in the Drive Exception Management region of the NVSRAM.
  • Different versions of NVSRAM will have different settings for primary and secondary drives to accommodate a variety of solutions.
  • When a drive exceeds the error thresholds determined by the NVSRAM, the drive will be failed.

Primary drive types consist of the following:

  • Fiber Channel (FC) drives
  • Serial Attached SCSI (SAS) drives.
  • Non-Volatile Memory Express (NVME) drives.

Secondary drive types consist of the following:

  • Serial Advanced Technology Attachment (SATA) drives.
  • Near Line SAS (NL SAS) drives.

Drive Error Thresholds consist of

  • A specified number of events
  • Types of events
  • A window of time

While the Drive Error Threshold settings in the NVSRAM can be modified manually, you are strongly advised against doing so. If the current settings in the NVSRAM are not to the desired specifications, it is recommended to load a different version of NVSRAM, which is preloaded with the desired settings

Note: Each controller has a separate PFA counter, this is by design to prevent excessive traffic. If the threshold is not exceeded on a single controller the drive will not be failed.

EXAMPLE: Failure threshold = 2 hardware errors in 1 hour.

A drive logs 2 hardware errors in 30 minutes. On the surface, this appears to clearly exceed the threshold limit. However, if each error is logged by a different controller, 1 by A and 1 by B, the drive will not be failed as the PFA threshold has not been exceeded by either controller.

 

Additional Information

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