S/390 Partners in Development

OPTI-CACHE at Rolamentos Schaeffler Do Brasil Ltda.

In early April 1996, Rolamentos Schaeffler Do Brasil Ltda. (a German metallurgic plant producing bearings for the automotive industry) was trying all the tricks for tuning VSAM files to improve their CICS response time. Rolamentos Schaeffler Do Brasil Ltda's configuration included a 9121-210 with 128MB of memory, VM/ESA 1.2.1 with VSE/ESA 1.3.5 test and production guest machines. DASD included 3380 J/K units attached to a 3990-2 controller. The production guest machine was 64MB V=V with dedicated DASD and had two CICS systems with 600 users each. Naturally, with this configuration they felt they should have faster response times.

Their most important file is the MANTIS file. After tuning was completed, the MANTIS files' average access time was reduced from 0.025 to 0.020 seconds. This file is accessed very frequently by the on-line CICS systems 600 users. Each CICS system averages 225,000 transactions per day. The file with the worst response time was the IESCNTL file with an average access time of 0.035 seconds. Mr. Carlos A. Bodra (a systems programmer since 1981) looked for help by posting a message on the VSE-L internet newsgroup (bit.listserv.vse-l). Barnard Software, Inc. (BSI) responded to Carlos by suggesting that additional tuning would be ineffective for those files. Instead, BSI suggested Rolamentos Schaeffler Do Brasil Ltda. eliminate the I/O to improve on-line response time and batch run times. The simplest solution would be to try OPTI-CACHE. OPTI-CACHE is a high speed virtual storage software caching product specifically designed for the VSE/ESA operating system.

"OPTI-CACHE was one of the easiest products that I have installed, one simple job of MSHP or LIBR and the product is up and running without any modifications of our system, application, JCL, etc ... It is a true plug-and-play piece of software" admits Mr. Bodra. But that was only the beginning of the good things to come. Setting up a 16MB dynamic partition for OPTI-CACHE changed their entire schedule for on-line and batch processing. With OPTI-CACHE running, the MANTIS file now had an average access time of 0.003 seconds and the IESCNTL files average access time was reduced to 0.005 seconds. Overall, CICS response time was reduced by 40%, from 0.5 seconds to 0.3 seconds.

And that was only half of the story. Their nightly batch processing runs were also about to be changed forever. Mr. Bodra relayed to BSI the following situation: "I remember I put OPTI-CACHE in production Friday afternoon and every Friday night we have a big batch load because of an MRP run. The night window starts at 8:00 PM Friday and ends at 7:00 AM Saturday morning. At 3:30 AM my phone at home rang and the night operations' supervisor was telling me something was wrong with the MRP run because the load had already finished. Something had to be wrong. After dialing in and rechecking all loads, all jobs ran as designed. Then I checked the FAQS-PCS accounting statistics and saw what happened. I/O had changed everything. We had some jobs that historically did 270,000 I/O's now only did 60,000 I/O's. We had jobs that dropped from 90 minutes to 20 minutes wall-clock time. I told the night operator everything was OK and goodnight. Monday our manager asked what happened: `Is the MRP correct?' Yes, everything is running as expected."

Rolamentos Schaeffler Do Brasil Ltda. had the following on-line/batch windows:

Before OPTI-CACHE:

On-line from 6:00 AM to 8:00 PM
Batch from 8:00 PM to 6:00 AM

After OPTI-CACHE:

On-line from 3:00 AM to 9:00 PM
Batch from 9:00 PM to 3:00 AM

Overall file access time dropped from 0.120 to 0.90 seconds, CPU time dropped from 2:30:00 over 14 hours to 2:20:00 over 18 hours now. The VSE machine working set did increase from 12K to 15K pages due to the storage used by the new OPTI-CACHE dynamic partition.

"OPTI-CACHE payed for itself the first month we used it. It was only necessary to know wall-clock minutes, CPU seconds and our I/O activity to show this. OPTI-CACHE is less expensive and less complicated than hardware cache and more efficient. We are very happy to be working with BSI and using their products." Carlos A. Bodra - June 1996