Admin executor pick ranked idle workers only, so a job whose volume
lived on full-03 could still run on full-01 and pull the whole .dat
across the LAN. Rank workers whose Hello host matches any replica
first (fallback to others if the local worker is full).
Detection named Sources[0] / the lowest server id; execute then
SyncAndSelectBestReplica and could switch the copy source to another
rack. After sync, if a replica on this machine has a complete file
count, copy from that URL so affinity and pull stay on one host.
Chepurnov Simon
84aff673c2