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Feature #14909

Updated by Jason Dillaman about 8 years ago

Assume an journal layout like: 

 Object 0:                                 Object 1: 
 tag=0 (class 0), tag=0, entry=0       tag=2 (class 0), tag=0, entry=1 
 tag=1 (class 1), tag=1, entry=0       tag=1, entry=1      
 tag=2 (class 0), entry=0      

 Replay 

 If tag 0 and 1 are within the same tag class, replay should detect that tag=2 is a replacement of tag=0. apply tag=0, entry=1 before applying tag=1, entry=0.    We should store metadata in the class to link a This will be important when multiple tag classes can be allocated to its predecessor so that it is known what the last processed tag was same journal (i.e. when a new tag was created (important for librbd if it opens a new epoch on a partially flush / missing entries journal). consistency groups are added).

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