ANBOB™

DRM is driven by the following
1.) _gc_affinity_time = Time in minutes at which statistics will be evaluated (default = 10 mins)
2.) _gc_affinity_limit = # of times a node accesses a file/object (default = 50)
3.) _gc_affinity_minimum = minimum # of times per minute a file/object is accessed before affinity kicks in
(default = 600 per minute per cpu )
4.) _lm_drm_disable = LEVEL disable drm in different level( default=0 )
Level 4 disable read mostly
Level 5 disable DRM for all but undo
Level 7 disable DRM for all including undo.

Disable DRM in 12C and onward

Shutdown all nodes after setting _lm_drm_disable=7, and then startup them. To disable DRM, instead of _gc_policy_time, _lm_drm_disable should be used as it’s dynamic(had bug).

alter system set “_lm_drm_disable=7” scope=spfile sid=’*';

Disable DRM in 11g Release 1 and onward

alter system set “_gc_undo_affinity”=FALSE scope=spfile sid=’*';
alter system set “_gc_policy_time”=0 scope=spfile sid=’*';

Disable DRM  In 10g

alter system set “_gc_undo_affinity”=FALSE scope=spfile sid=’*';
alter system set “_gc_affinity_time”=0 scope=spfile sid=’*';

Note:
因为上面两个参数是静态，修改需要重启，通过修改下面两个动态参数也可以减少DRM 的效果:

10g

alter system set “_gc_affinity_limit”=250 sid=’*';
alter system set “_gc_affinity_minimum”=10485760 sid=’*';

11g

alter system set “_gc_policy_minimum”=10485760 sid=’*';

12c+

alter system set “_gc_policy_minimum”=10485760 sid=’*';

Note:
From 11g onwards, affinity management renamed to policy management. For example, x$object_affinity_statistics is renamed to x$object_policy_statistics. Similarly, initialization parameters are renamed too:Parameter _gc_affinity_limit is renamed to _gc_policy_limit; Parameter _gc_affinity_time is renamed to _gc_policy_time; A new view v$policy_history is introduced and all rows with policy_event = ‘initiate_affinity’ are associated with DRM events.

To disable DRM completely, set _gc_policy_limit and _gc_policy_minimum to much higher value, say 10Million. Setting the parameter _gc_policy_time to 0 will completely disable DRM, but that also means that you can not manually remaster objects

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