# Changing the write-cache mode on a logical drive

(Startable-CD mode only.)

Use this action to change the write-cache mode setting of a logical drive to write through or write back. The write-cache mode determines if the controller writes data to the drive before or after sending a confirmation to the operating system.

Notes:
  1. (RAID level-x0 only.) All logical drives in a spanned array must be either write back or write through. That is, the write-cache mode settings for the logical drives in the spanned array cannot be a mixture of write back and write through.
  2. (Failover environment only.) A fault-tolerant controller pairing must be configured as write through. This is because the logical drives are configured as "Shared." For more information, refer to the IBM ServeRAID-4 Ultra160 SCSI Controller User's Reference.
  3. (Cluster environment only.) If the logical drives are configured as "Shared," the controllers must be configured as write through. For more information, refer to the IBM ServeRAID-4 Ultra160 SCSI Controller User's Reference.

1. In the tree, click (logical drive).
2. Right-click Change write-cache mode to write back or write through.
3. If you click write back and you do not have a battery-backup cache, click Yes to confirm your choice because there is a risk of losing data.
   If you click write back and you do have a battery-backup cache, the ServeRAID Manager changes the mode.
   If you click write through, the ServeRAID Manager changes the mode.

## More information

- Understanding write-cache mode for logical drives

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