IEBDG uses BSAM or QSAM (probably BSAM, but I don't know for sure and it doesn't really matter) to write buffers. By default, the number of buffers is normally about 10, which means an average 5 buffers per I/O.
ICEGENER will do larger chunks of I/O using EXCP, thus the lower SIO rate and higher transfer rate. If you use real IEBGENER you will probably see similar rates for both. Or, you can specify a BUFNO=99 on the DD statements for IEBDG and IEBGENER and probably see about the same rates as ICEGENER. Christopher Y. Blaicher BMC Software, Inc. Austin Development Labs (512) 340-6154 The comments made are my personal opinions. BMC Software, Inc. makes no representations or promises regarding the reliability, completeness, or accuracy of the information provided in this discussion; all readers agree not to rely on this information or take any action against BMC Software in response to this information. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of R.S. Sent: Monday, February 05, 2007 11:47 AM To: [email protected] Subject: SIO in SDSF vs read/write speed I made the following observation: 1. WRITE. I put some data to tape (3592J). The average transfer speed was approx. 70MB/s. SDSF shows very high SIO rate for the job, approx. 2500. Data generated by IEBDG, blocksize=32720, RECFM=FB, LRECL=80 2. READ. I read *the same* data, which I previously wrote. Got even higher transfer speeds, approx. 100MB/s,but significantly lower SIO rate, approx. 40 Dataset (FB 80 32720) read by ICEGENER. 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 ? -- Radoslaw Skorupka Lodz, Poland ---------------------------------------------------------------------- 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
