Network Metrics Requirements and Usage for WP1

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Network Metrics Requirements and Usagefor WP1

• Tiziana Ferrari
• Tiziana.Ferrari_at_cnaf.infn.it

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Applicability examples

• Integration of network info into the scheduling
  policy
• To define the most suitable Storage Element for
  one or more Computing Elements
• Triggering of data transfers
• To gather in a single Storage Element portions of
  data sets partioned among several Ses
• List of applications to be developed further

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Network information

• CloseSE attribute
• CloseSE (closeness1, SE1), , (closenessn,
  SEn)
• closeness(CE, SE) max 0ltiltm, 0ltjltn
  closeness(CEi,SEj)
• Closeness varies in 0,1
• 0 SE unreachable
• 1 SE on the same LAN
• Definitions
• r Round Trip Time, Rmax max RTT,
• ploss packet loss frequency
• th throughput thmax maximum throughput
• closenessi,j (ploss ,r,th) 0 if ploss ? 0
• closenessi,j (ploss ,r,th) th / thmax ?
  r/ rmax where 0 lt?
  lt 1 otherwise

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Closeness i,j(p,th,r)
Fig 1 alpha 1/2
Fig 2 alpha 1/10
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Triggering of data transfers

• Problem statement
• Input data requested by a given job running on CE
  is partioned and portions are stored in different
  SEi
• Input data needs to be gathered in a single SE
  and the most appropriate one has to be selected
• Selection creteria
• Amount of data in each SEi
• Network distance between two SE
• Closeness of SEi to CE under consideration
• SE is the selected Storage Element for acomputing
  element CE iff
• SE SEi iff D(SEi) minj ? D(SEj) ?
• where D(SEi) is a SE Distance function.

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SE Distance function D

• CASE 1 data in each SEi not known, SEi
  equivalently distant to CE
• D(SEi) ? 1? j? n, j? i closeness(SEi ,
  SEj )
• CASE 2 SEi equivalently distant to CE
• D(SEi) ?max/ ?i ? 1? j? n, j? i
  closeness(SEi , SEj ) ?max/ ?i
• ?i amount of data in each Sei
• ?max amount of data requested by a given job
• CASE 3
• D(SEi) ? closeness(CE, SEi) ?max/ ?i ? 1?
  j? n, j? i closeness(SEi , SEj )
• ? constant in 0,1