Storage Classes

The definition of "tape & "disk" is as follows:

  • disk: "fast" access; cache copy
  • tape: "slow" access; archival

LHCb have identified 5 classes:

Class A
  • permanent copy on "tape" only, no requirement for long-termed "pinned" disk copy; data set will be accessed 1/2 per year e.g. RAW or rDST data during which data set will be "pinned" on cache

Class B
  • permanent copy on "tape"; "pinned" disk copy under control of LHC production e.g. DST for analysis at CERN, DST for analysis at Tier-1 centres they were produced

Class C
  • "infinite pinned" disk copy under control of LHCb production e.g. DST for analysis at Tier-1 where a copy is on "tape" at another Tier-1

Class D
  • "pinned" disk copy under LHCb user control; copy on "tape" for back-up; c.f. CERN AFSLoginProblems. Note: these files could be small

Class E
  • "pinned" disk copy under LHCb user control; no "tape" copy i.e. scratch area with controlled lifetime
-- NickBrook - 04 Apr 2006
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Topic revision: r2 - 2006-11-16 - unknown
 
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