USE CASE STORAGE

File names and paths should be treated as "logical" and should never be
accessed directly by bookkeeping. Conversion logical <--> physical should
be handled by storage system.

Bookkeeping should not constrain people how they organize data. Examples:
 - which mass storage they should use
 - how much online/offline space needed for data.
  E.g. bookkeeping should not require some large
  components to reside on disks.

[Not sure if the next two are more related to event store or bookkeeping]

File sizes larger than 100 MB
 - to utilize tape devices efficiently

Total number of files <10-20 millions E.g. current system at SLAC was
sized to handle several million files.

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