Tiziana Ferrari Network Metrics Requirements and Usage for WP1 1

Network Metrics Requirements and Usage

for WP1

Tiziana Ferrari

Tiziana.Ferrari@cnaf.infn.it

Tiziana Ferrari 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…

Tiziana Ferrari 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

Tiziana Ferrari Network Metrics Requirements and Usage for WP1 4

Closeness function

Fig 1: alpha = 2 Fig 2: alpha = 10

Tiziana Ferrari 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