I have found several different equations to calculate the correct blocking factor when utilizing NBRRCDS in a CL to optimize I/O. One stated (128k)/(reclength), another (128k)/(reclength+1), another (1024*256)/(reclength) and still another (131072)/(reclength+1), with different variations in the record length and the additional one-byte. If the total record length of my file is 104 (DSPFD), how would I determine the correct and most efficient record blocking length? Does the iSeries block in 256k inrements? We have a batch job that is slowly growing longer and longer in runtime each night without a comparable increase in file size. Running out of ideas.