SyncSort can copy a data set in a variety of ways. The first way is to read a block of data, move each record to an output buffer and write the block of data. The other way is to read a block of data and immediately write it out without deblocking the data. The advantage is that the 2nd method is much better from a cpu perspective. The second method will only be used if there is no "per-record" action such as reformatting or record selection and if the input and output blocksizes are the same. The downside of the second method is if there are short blocks they will appear in the output.
John Reda Syncsort, Inc. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of ??? ?? ??? Sent: Wednesday, December 31, 2008 6:56 AM To: [email protected] Subject: Syncsort Oddity Hi, I've encountered something in Syncsort, and I'm looking for an explanation. One of our users used Syncsort to copy a dataset. The input file had 93386 tracks in 10 extents. The output file had 64815 tracks in 2 extents. Both files are LRECL=27904 BLKSIZE=27998 RECFM=VB DSNTYPE=LARGE. The copy job used Syncsort's SDB=ON option Both are allocated on the same type of DASD (3390-54). When we say the 30% difference in size we used IEBCOMPR to compare the two file, and the result was that they were identical. Another test was done. This time, Syncsort was used to copy records that had a specific value in a specific field. On the large (Input) file, the job ran for 64 seconds. On the small (Output) file the same operation took 7 seconds. Can anyone explain this? TIA Gadi ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
