Documentation/scsi/sd-parameters.rst

.. SPDX-License-Identifier: GPL-2.0

======================================
Linux SCSI Disk Driver (sd) Parameters
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cache_type (RW)
---------------
Enable/disable drive write & read cache.

===========================   === ===   ===========   ==========
 cache_type string            WCE RCD   Write cache   Read cache
===========================   === ===   ===========   ==========
 write through                0   0     off           on
 none                         0   1     off           off
 write back                   1   0     on            on
 write back, no read (daft)   1   1     on            off
===========================   === ===   ===========   ==========

To set cache type to "write back" and save this setting to the drive::

  # echo "write back" > cache_type

To modify the caching mode without making the change persistent, prepend
"temporary " to the cache type string. E.g.::

  # echo "temporary write back" > cache_type