Security is one of the classic strengths of the S/390 and zSeries platforms and especially of z/OS. RACF is the centerpiece of z/OS security. RACF provides extensive security with the best possible performance. Because more and more products integrate their security into RACF, RACF has evolved many ways to ensure rapid access to security data.

Any claims that IBM is focusing on RACF performance because of alleged performance problems are absolutely false. RACF's focus on performance is to maintain and enhance the industry leading performance of RACF and of MVS.

In fact, a financial services company in the southwest had this to say after moving their production workloads to RACF:

The performance impact of the implementation of RACF in production has been very positive. Forty-five fewer DASD I/Os per second are being performed to the production RACF security data bases than ACF2 required. RACF's support for exploiting the GRS capability to convert hardware reserves on the data base volume to global enqueues has also eliminated a source of frequent slowdowns and occasional outages with ACF2. The implementation of RACF has improved availability and performance (and significantly reduced software license costs) in all environments.

RACF... proven performance!

Let's spend a few moments discussing how RACF provides lightning-fast response. Note: The techniques described below are proven ways that RACF has addressed performance. Your environment determines the effectiveness of each of these techniques. IBM is not making any formal performance test results available. As always, your mileage may vary.

One of the key elements in the performance of any software is the amount of input and output (I/O) activity. Traditionally, I/O devices have been markedly slower than processors. This is the driving force behind the need for intelligent data buffering mechanisms.

RACF has extensive facilities that reduce I/O activity, replacing it with the far faster in-memory operations. Of course, above-the-line storage is used wherever possible for maximum storage efficiency. In fact, before an I/O is performed, RACF has many levels of buffering that it can use before an I/O needs to be initiated. These levels are:

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