LHCb Space tokens migration happened in April 2011

New space tokens schema

LHCb wanted a simplification in Storage Element Space Token definition, from the old configuration:
LHCb-RAW T1D0
LHCb-RDST T1D0
LHCb-M-DST T1D1
LHCb-MC-M-DST T1D1
LHCb-DST T0D1
LHCb-MC_DST T0D1
LHCb-FAILOVER T0D1
LHCb-USER T0D1
To a simpler:
LHCb-Tape T1D0
LHCb-Disk T0D1
LHCb-USER T0D1
put in place at all sites during April - May 2011.

The migration has been done in different ways, according to the different storage technology at the sites:

For Castor and StoRM: the files have been migrated from old space tokens to new ones with this mapping:

  • LHCb-RAW , LHCb-RDST to LHCb-Tape
  • LHCb-M-DST, LHCb-MC-M-DST, LHCb-DST, LHCb-MC_DST, LHCb-FAILOVER to LHCb-Disk
  • LHCb_USER has stayed the same.

in dCache the procedure was different. It was coordinated by Ricardo together with PIC people and it served as example to other dCache sites. See this document: spaceTokenMigrationProcedure enclosed to this page.

Some question from sites administrators

  • How often should space be re-allocated from old space tokens to new ones? Answer: it has been agreed with sites that LHCb will notify the site via GGUS ticket when it will necessary to do it (typically after a removal campaign)
  • When will the old space token be completely cleared? Answer: the LHCb_RAW and LHCb_RDST never. The LHCb-M-DST, LHCb-MC-M-DST, LHCb-DST, LHCb-MC_DST will be gradually cleared. But for the LHCb computing team it is impossible to say when all data will be removed, because data removal is an operation to be agreed with the physics groups
  • When some space is re-allocated, to which space token should it be allocated? Answer: to LHCb-Disk. Unless LHCb explicitly asks to add it to other space tokens.
  • How much space should be left in the old T1D1 space tokens? Answer: only the space actually occupied by the files residing there. All the remaining free space should be removed from there. LHCb will never write there, only read.

-- ElisaLanciotti - 07-Oct-2011

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Unknown file formatodt spaceTokensMigrationProcedure.odt r1 manage 14.7 K 2011-10-07 - 12:40 UnknownUser document describing the procedure for the space token migration for dCache
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Topic revision: r2 - 2011-10-07 - unknown
 
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