Ken, I believe that DFW cannot be turned off on 2105 and 2107 emulation.
CFW can still be set inactive, but the recommendation for HDS is to leave it turned on. CFW reduces cache usage significantly as there is only one copy of the write, and the CFW queues are treated differently to DFW. There were some urban myths that CFW could flood cache with deferred writes, but urban myths is what they are. With TrueCopy you also have the option inhibit replication of CFW, the logic being if the application decides it doesn't need two copies, then why remote copy data is not needed for restart. For GDPS we turn CFW off as per IBM's requirements for the DS8K products. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] > On Behalf Of Ken Leidner > Sent: Tuesday, October 30, 2012 7:59 PM > To: [email protected] > Subject: [IBM-MAIN] DASD and Cache Fast Write & DS8800/DS8700 > > Does setting the DASD FW or Cache FW on or off still exist on the > DS8800/DS8700 devices. I know when they first came out for a 3990-6 > controller, the performance different was night and day. > > But on the newer devices isn't it always on? Can I really still turn it off? Do I > still need to check to make sure it is on? > > Ken Leidner [email protected] > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
