[linux-block.git] / Documentation / scsi / sd-parameters.rst

.. 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
Commit	Line	Data
d835971b MCC	1	.. SPDX-License-Identifier: GPL-2.0
	2
	3	======================================
	4	Linux SCSI Disk Driver (sd) Parameters
	5	======================================
	6
	7	cache_type (RW)
	8	---------------
	9	Enable/disable drive write & read cache.
	10
	11	=========================== === === =========== ==========
	12	cache_type string WCE RCD Write cache Read cache
	13	=========================== === === =========== ==========
	14	write through 0 0 off on
	15	none 0 1 off off
	16	write back 1 0 on on
	17	write back, no read (daft) 1 1 on off
	18	=========================== === === =========== ==========
	19
	20	To set cache type to "write back" and save this setting to the drive::
	21
	22	# echo "write back" > cache_type
	23
	24	To modify the caching mode without making the change persistent, prepend
	25	"temporary " to the cache type string. E.g.::
	26
	27	# echo "temporary write back" > cache_type