Commit cd039afa authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm writecache: add "cleaner" and "max_age" to Documentation 



Backfill missing Documentation.

Fixes: 93de44eb ("dm writecache: implement the "cleaner" policy")
Fixes: 3923d485 ("dm writecache: implement gradual cleanup")
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 867de40c

Documentation/admin-guide/device-mapper/writecache.rst

+17 −0
Original line number Diff line number Diff line
@@ -53,6 +53,21 @@ Constructor parameters: 


		- some underlying devices perform better with fua, some

		  with nofua. The user should test it

	cleaner

		when this option is activated (either in the constructor

		arguments or by a message), the cache will not promote

		new writes (however, writes to already cached blocks are

		promoted, to avoid data corruption due to misordered

		writes) and it will gradually writeback any cached

		data. The userspace can then monitor the cleaning

		process with "dmsetup status". When the number of cached

		blocks drops to zero, userspace can unload the

		dm-writecache target and replace it with dm-linear or

		other targets.

	max_age n

		specifies the maximum age of a block in milliseconds. If

		a block is stored in the cache for too long, it will be

		written to the underlying device and cleaned up.



Status:

1. error indicator - 0 if there was no error, otherwise error number
@@ -77,3 +92,5 @@ Messages: 
		5. resume the device, so that it will use the linear

		   target

		6. the cache device is now inactive and it can be deleted

	cleaner

		See above "cleaner" constructor documentation.