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Commit 18d595bf authored by Weiping Zhang's avatar Weiping Zhang Committed by Martin K. Petersen
Browse files

scsi: sd: Documentation: add sd-parameters.txt 



Add a file for documenting SCSI sd module parameters and describe the
cache_type setting.

[mkp: tweaked text a bit]

Signed-off-by: default avatarWeiping Zhang <zhangweiping@didichuxing.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 29e79e0f

Documentation/scsi/sd-parameters.txt

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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