Network Metrics Requirements and Usage for WP1

1. Network Metrics Requirements and Usagefor WP1 Tiziana Ferrari Tiziana.Ferrari@cnaf.infn.it Network Metrics Requirements and Usage for WP1

2. 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… Network Metrics Requirements and Usage for WP1

3. Network information • CloseSE attribute: • CloseSE = {(closeness1, SE1), …, (closenessn, SEn)} • closeness(CE, SE) = max 0<i<m, 0<j<n {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 << 1 otherwise Network Metrics Requirements and Usage for WP1

4. Closeness function Fig 1: alpha = 2 Fig 2: alpha = 10 Network Metrics Requirements and Usage for WP1

5. Triggering of data transfers • Initial assumption: all the SEs in a given set SElist =(SE1 , SE2 , …, SEn ) are equally distant from a given CE • Definitions: • Inter SE distance: D(SEi) =  1 j n, j i closeness(SEi , SEj ) • I: data portion stored by each SEi • Optimization function: opt(SEi) = minj D(SEj) * i/ max where  in [0,1] • SE is the selected Storage Element for computing element CE iff: SE = SEi iff opt(SEi) = minj D(SEj) * i/ max Network Metrics Requirements and Usage for WP1