Lifecycle tiering

When does moving data to a cold tier save money?

Cloud providers offer cheaper cold tiers. Moving an object to a cold tier is a prediction problem with asymmetric costs, made before the access is observed.

A cold tier sells a lower storage rate in exchange for retrieval fees and minimum durations, so tiering pays only when an object's dormancy exceeds retrieval fee ÷ monthly saving (the pricing is cost mechanics'; at typical prices about 3.5 months). The maintenance problem is that the move is decided before the next access is seen, from access history the job may not have.

Transitions are also per-object requests. A table made of small files is therefore expensive to tier as well as to read. (This is again granularity mismatch producing amplification: one more cost per file.)