Skip to main content
NetApp Knowledge Base

How to troubleshoot E-Series Write back caching forcibly disabled alert

Views:
4,945
Visibility:
Public
Votes:
4
Category:
e-series-systems
Specialty:
esg
Last Updated:

Applies to

NetApp E-Series

Description

This article describes the procedure to troubleshoot "Write-Back Caching Forcibly Disabled" on E-Series systems.

Write-back caching was disabled on one or more volumes. This problem can occur for the following reasons:

  • Battery Failure
  • Battery below minimum capacity
  • The cache size memory of the controllers are different
  • Cache Reconfiguration 
  • A Cache Data-Restore operation is in progress, which interrupted the normal write-back caching process
  • The space in the cache backup device is insufficient for storing the cache
  • Memory parity error
  • Simplex configuration - cache cannot be mirrored

Important Notes

  • When write-back caching is enabled when volumes are configured, write-back caching improves I/O performance. When write-back caching is disabled, the system goes into write through mode, meaning that the I/O will get acknowledged after it is written to disk rather than when it is written to cache. In such case, I/O performance to the volume or group of volumes can be seriously degraded depending on the drives. 
  • The error triggers a critical event. 
  • The controller is in the Notified state. When write-back caching is enabled, the system transitions from Notified to Optimal after all volumes configured to use write-back caching are restored. 
  • When the system transitions from Notified to Optimal, an information MEL event is logged to show that all normal write-back caching capabilities are restored for all volumes in the system. 
  • While in the Notified state, a forced-disable of write-caching on any additional volumes has no effect, and no state transition occurs. 

 

Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.