Incremental Architecture Allows Bank To Expand Its On-Line Data Capability.
Namely, he looked at exchanging either the bank's NCR V-8570 computer or its companion V-8575 processor for a "dyadic" or "tightly coupled" system featuring twin V-8500 Series processors in a single cabinet.
"But, knowing that a new family of our vendor's processors (V-8600 Series) was coming out, we decided to add only these systems as we grew," Hopkins recalls. "Yet, at the same time, we wanted to keep our V-8500 computers up and running, primarily because we already had paid for them. The ability to loosely couple our existing computers with a new V-8635 processor gave us the best of both worlds."
Today, the $494-million bank is the first financial institution in the country to have tapped NCR "incremental architecture" capabilities for planned, low-cost mainframe growth and peripheral pooling. Incremental architecture describes a new add-on approach to system expansion, which keys on enhancements to the vendor's VRX (Virtual Resources Executive) operating system and new hardware components. Why a Loosely Coupled System?
Why link two or more computers in a loosely coupled environment?
"In the past, each of our shop's 20 (NCR 685) disk drives were dedicated to a single processor," Hopkins says. "That complicated job scheduling, since we never knew which drive an operator might allow us to use. Our loosely coupled environment eliminates this problem, because our three processors can share any device that uses bit-serial link technology. That includes disk drives, tape drives and printers. In fact, the only peripherals we can't pool are common-trunk controllers and sorters. Today, our 200-megabyte disk drives connect to our processors through five NCR 6589 controllers. In general, the more drives on a controller, the more potential for bottlenecking problems. So, by reducing the number of drives per controller, we've reduced contention problems."
To allocate a peripheral to a processor, a First-Citizens' computer operator simply keys a command into the "host" processor's operating console. This ability to electronically switch peripherals has saved the bank significant sums of money by eliminating the need to purchase and install duplicate peripherals for its new system. Why Not a Tightly Coupled One?
While First-Citizens opted for a loosely coupled environment, Hopkins notes that tightly coupled systems have their applications. He cites power, performance and load-leveling as advantages. Also, he points out that tightly coupled systems require only one copy of the operating system and run with a single job stack.
"But, when you lose your tightly coupled system, you're dead," adds Hopkins. "In contrast, loosely coupled environments are very fault tolerant. If we lose one of our coupled processors for any reason, the other processors continue on. This high availability is what is most important to us."
First-Citizens' emphasis on high availability is easy to understand. The bank's on-line computer system currently supports a total of 535 terminals located in 65 South Carolina branches. By year-end 1984, there'll be even more on-line terminals since the bank is building four new offices, and a merger with South Carolina National Bank and First National Bank of South Carolina recently added 15 branches to be folded into First-Citizens' on-line network.
In addition, First-Citizens' on-line capabilities now must stand up to customer comparison tests. The bank is a founding member of "Relay," a new-25-bank automated teller machine (ATM) network that gives customers of these banks access to 800-plus ATMs in the Carolinas and Virginia. Hopkins' programming staff spent seven months writing the Relay software that connects the bank's network with a central computer in Raleigh, North Carolina, to furnish real-time on-line information on its own customers' balances and to give it the ability to make its own inquiries on "foreign" customers.
"For customers who use our ATMs, we target on a 2.5-second transaction time," says Hopkins. "That's 2.5 seconds from the time a customer enters a card until the requested cash is in hand. We've picked up some customers simply because our on-line system and, hence, our ATMs are faster." Why Uptime Becomes More Crucial
A point-of-sale (POS) network, due to go live by year-end, will up the on-line ante, too. First-Citizens plans to distribute plastic debit cards for customer use at grocery and department store checkout counters. "When this happens, uptime for our on-line system will be even more crucial," Hopkins says. "If someone's checking out of a supermarket with four bags of groceries, and plans to pay with a debit card on a POS terminal, that person is not going to be very understanding if the computer is down."
Having explained the "why" of loose coupling, Hopkins delves into "how" it's accomplished. He notes that a 16 by 32 dynamic channel director (DCD) lets the processors "handshake," while another piece of hardware, the system-to-system adaptor, acts as a mailbox. On the software side, a VRX Inter-Host Management System keeps tabs on which computer is designated manager host, which are standby hosts, and what processor "owns" a given peripheral at any point in time.
"The hardware and software work in tandem to constantly relay 'I'm OK' messages between processors," says Hopkins. "If one processor should go down, say the system that we use for key on-line applications, a message to that effect immediately appears on each processor console. At that point, we can re-enable the processor or run in a dual-processor environment, with one of the other processors running the down unit's on-line jobs. Software Speeds Switchover
"As soon as we bring up NCR InstantReady software, a communications line switch will transfer on-line tasks from one processor to another in less than two minutes, rather than the 15 to 30 minutes a switchover takes with some systems," he adds. With that software, specifically designed for critical on-line applications, one processor passes all its information to another every four to 25 seconds.
Hopkins notes that the DCD connection allows the loosely coupled processors to share files, which permits jobs to be offloaded from one processor to another and boosts throughput. However, he points out that a danger exists. "Unless you're using the protection features of VRX, you're wide open to the possibility of two processors attempting to update the same file at the same time," he says.
With three processors available, operators can match program application service requirements to processor availability and speed. Generator Gives Power Protection
To further enhance uptime performance, First-Citizens has installed a motor generator to give its V-8635 system a six-second ride through when power fluctuations cause brief outages. "This particular device has enabled us to keep that system up 99.5 percent of the time rather than 99 percent of the time," says Hopkins.
However, the manager points out that this generator, designed to meet the V-8635 system's special 60-cycles-in, 400-cycles-out requirements, offers no power protection for peripherals or the two 8500 Series machines, which run on three-phase, 60-cycle input. "We're looking at the possibility of getting another 60-cycle generator to protect these devices," says Hopkins. "And, eventually, we would like to have a full 30 minutes of backup power for our systems."
Once First-Citizens settled on its loosely coupled route to system growth, a benchmark test clearly illustrated the processing speed gains offered by its system addition. Jobs chosen for the benchmark comparison of the V-8635 and V-8570 processors included J-Update and J-Strip jobs, which are crucial to banks such as First-Citizens that rely on NCR's CIF-FOCIS (Customer Information File and Financial On-line Customer Information System) software packages. Test Times System Swiftness
"The figures were a dead giveaway on which system is fastest," says Hopkins. "With the V-8635, elapsed time was cut in half, while throughput increased abut 46 percent. The J-Update job uses about six or seven programs to balance totals and update the CIF master file in a batch environment. With our old configuration, this job took two hours and eight minutes. With the new system, J-Update time dropped to one hour, 33 minutes, despite input-output (I/O) contention. The J-Strip job strips information from the master file to create an on-line inquiry file. With the V-8635, we can complete J-Strip processing in two hours and 44 minutes, a full hour faster than on the V-8570. Without any fine-tuning of programs, V-8600 system cycle time was 32 percent faster."
Hopkins says these speed gains help the bank complete processing by 5 am to meet air and ground-courier deadlines.
"With our new system, we can start processing at about 8 pm and finish the updating and building of on-line files by 2 am," he says. "This gives us two to three hours of fallback time for emergencies. Given the time this system has bought us in terms of our processing window, we will have no problems handling the additional volume that new branches will add.
"I'd recommend a V-8600 Series machine to any data processing shop looking at high throughput and large transaction volumes," he adds. "Operators will love you because they'll go home earlier at night. But, most importantly, this system is very cost effective."
During First-Citizens' testing phase, Hopkins say he learned a lot about the new processor and why it's faster. For instance, he points out that its 128K cache memory lets the machine find information much faster. "When you have to look up every telephone number you call in a city directory, it takes a lot longer than if you have all the numbers you call regularly in a personal phone book," he says. "That's what cache memory does for the processor." Translator Enhances Throughput
He adds that the new system's larger dynamic address translator board enhances throughput by minimizing the number of places to be checked for page faults, while a micro-instruction set permits some compiling of instructions. Input/output architecture also has improved with the addition of a separate I/O or channel control processor, he notes.
Since it installed its V-8635 system in October 1983, First-Citizens has experienced only the minor problems one expects as a test site, the manager comments. He stresses that the addition of the new system and a, changeover to a loosely coupled environment entailed no massive programming or operator training effort.
"We didn't have to change any of our CIF-FOCIS programs when we went to the 8600," says Hopkins, who as president of the North American NCR Financial Users Group recognizes the importance of migration-path engineering. "Everything has been upward compatible. We just connected the new hardware, and we were up and running just like the day before. In the new loosely coupled environment, our operators encountered a few new commands, but no real training was needed. Our programmers were used to OLPD (on-line program development), which is no different on the new system." One Library Pack Serves Systems
However, the manager does note that VRX-II is the only copy of VRX that supports loosely coupled processors. He also explains that while First-Citizens runs three copies of the VRX-II operating system for its three systems, there is only one shared library pack.
"With three systems, we normally would need a VRX pack and a library pack for each," he observes. "This would mean trying up six drives with VRX. However, by sharing a library pack, we've cut this requirement by three drives."
To eliminate potential problems associated with having multiple copies of OLPD work files, only one copy is used and all updates are handled through the library pack on the V-8600 processor. A side benefit of the shared-library-pack approach had been the elimination of tedious and time-consuming weekend backup procedures. "Now, when we back up updated files, we don't have to move anything," he says.
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|Date:||Dec 1, 1984|
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