In a message dated 2/5/2007 11:47:22 A.M. Central Standard Time, R.Skorupka @ BREMULTIBANK.COM.PL writes: >I think, ICEGENER reads the data in much larger chunks, so the number of I/O is lower, but the speeds is even greater. Am I right ? Don't know if you are right that ICEGENER reads in larger chunks (block size and/or two or more block-reading CCWs chained together), but if true then that would account for the higher effective data transfer rate. Highest possible data transfer rate would be doing only one I/O request that has enough CCWs in it to read the whole tape. Anything less than this will result in lower than maximum possible data transfer rate. This is not practical in the general sense, as each read CCW needs page-fixed storage for the block it is reading, you don't know in advance how much data is on the tape, and the amount of storage needed to be page-fixed could easily be far more than all real storage on the system. Bill Fairchild
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