As I indicated, my primary exposure to this stuff was when CFW and DFW were first introduced. At that time, the respective caches were comparatively small. What I found was that once the cache was "flooded," the control unit would "hold off" new writes (delay execution of the channel program right after the LocateRecord) until enough data from cache could be destaged to DASD. This had more of a detrimental effect on overall elapsed time than not using CFW/DFW at all, and it was particularly exacerbated when writing concurrently to several sortworks that were all on the same control unit.
CFW is only used for sortworks since they are always considered to hold "temporary" data. DFW would be used for SORTOUT. I have no idea what the "no-go's" are these days, if any, but they used to take at least filesize into consideration. Art At 10:41 AM 1/20/2008, Bill Fairchild wrote: > >In a message dated 1/18/2008 8:52:20 P.M. Central Standard Time, >[EMAIL PROTECTED] writes: > >Yes, SyncSort does use CFW. I wrote the code myself in a previous life, >17 or so years ago. However, IIRC, there may be circumstances where it is >turned off due to other performance considerations. Check with SyncSort's >Customer Service if you need to know when, if ever these days. > > > >They may not choose to reveal such info. If the need to know is great >enough, one can always trace Syncsort for a while with GTF and study the >channel >programs. Then the real fun begins - perusing the formatted GTF trace >records >(not for the impatient or faint of heart). > ================================================== Art Celestini Celestini Development Services Phone: 201-670-1674 Wyckoff, NJ ============= http://celestini.com ============= Mail sent to the "From" address used in this post will be rejected by our server. Please send off- list email to: ibmmain<at-sign>celestini<dot>com. ================================================== ---------------------------------------------------------------------- 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
