.. SPDX-License-Identifier: GPL-2.0
  
  ======================================
  Linux SCSI Disk Driver (sd) Parameters
  ======================================
  
  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