You asked ... "We are wishing to migrate data according to the heat onto different storage categories (expensive --> cheap devices)"
We suggest a policy rule like this: Rule 'm' Migrate From Pool 'Expensive' To Pool 'Thrifty' Threshold(90,75) Weight(-FILE_HEAT) /* minus sign! */ Which you can interpret as: When The 'Expensive' pool is 90% or more full, Migrate the lowest heat (coldest!) files to pool 'Thrifty', until the occupancy of 'Expensive' has been reduced to 75%. The concepts of Threshold and Weight have been in the produce since the MIGRATE rule was introduced. Another concept we introduced at the same time as FILE_HEAT was GROUP POOL. We've had little feedback and very few questions about this, so either it works great or is not being used much. (Maybe both are true ;-) ) GROUP POOL migration is documented in the Information Lifecycle Management chapter along with the other elements of the policy rules. In the 4.2.1 doc we suggest you can "repack" several pools with one GROUP POOL rule and one MIGRATE rule like this: You can “repack” a group pool by WEIGHT. Migrate files of higher weight to preferred disk pools by specifying a group pool as both the source and the target of a MIGRATE rule. rule ’grpdef’ GROUP POOL ’gpool’ IS ’ssd’ LIMIT(90) THEN ’fast’ LIMIT(85) THEN ’sata’ rule ’repack’ MIGRATE FROM POOL ’gpool’ TO POOL ’gpool’ WEIGHT(FILE_HEAT) This should rank all the files in the three pools from hottest to coldest, and migrate them as necessary (if feasible) so that 'ssd' is up to 90% full of the hottest, 'fast' is up to 85% full of the next most hot, and the coolest files will be migrated to 'sata'.
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