System Architecture Design for GIS
Steve Garfield Reliant Energy PO Box 1700 Houston, Texas 77251-1700 Dave Peters Environmental Systems Research Institute, Inc. (ESRI) 380 New York Street Redlands, California 92373 Abstract Geographic information systems (GIS) are supporting a growing number of operational environments, taking advantage of distributed architecture and providing digital mapping solutions throughout electric- and gas-use environments. Hardware and networking technology is supporting a growing number of solutions, extending user access to company business systems from remote field operations to central boardrooms. Software solutions integrate business operations from the field to the desktop, providing direct connectivity to integrated database environments across the enterprise. Proper hardware and network support for distributed GIS computing is growing in importance. Understanding the available technology and design methodology to support and manage distributed computing environments provides a foundation for successful operational environments. This paper provides an update on current distributed GIS architecture solutions, and the current state of GIS-based enterprise operations. Reliant Energy will present an overview of their ArcFM 8 implementation supporting distributed edit operations with remote Windows Terminal Server (WTS) clients and replicated ArcSDE data servers supporting remote plotting requirements. A methodology for addressing distributed GIS operations is provided in a System Design Strategies white paper available at http://www.esri.com/library/whitepapers/pdfs/sysdesig.pdf. (Reliant Energy GIS Migration) Steve Garfield is responsible for a team of three who provide system support for servers for the GIS department of Reliant Energy. Steve’s team provides system administration support for Citrix, NT/2000, Sun Solaris, Web, multiple Oracle and Sybase databases, and over a terabyte of combined storage. Reliant Energy is a multi-national energy company with gas and electric distribution facilities located in Texas, Oklahoma, Louisiana, Mississippi, Arkansas, and Minnesota. Reliant Energy is headquartered in Houston, Texas, and has over 14,000 employees. Over 1,174,140 electric customers and 972,000 gas customers are located in the Houston area alone. The GIS department, managed by Jeff Myerson, is responsible for the digitizing, maintenance, and map production of GIS data for Reliant Energy. The GIS department also provides addressing for the City of Houston and several surrounding municipalities. The GIS department has over 80 staff including digitizers, support desk, technical support and management, supporting a full spectrum of GIS services to the company. GIS is a full support organization that works within the infrastructure provided by the IT department. GIS Migration In 1997, Reliant Energy was well along in a process to determine the best way to upgrade their existing GIS environment. Reliant was looking to implement an enterprise solution, and had several caveats that had to be met by the software infrastructure. A partnership was established with the selected vendor to develop this solution. The original suggested specifications are still in place and working well, even though some of the initial GIS software were a beta release. The GIS shop consists of a mixed environment. Sun Microsystems servers are used for large databases. The main production box is an Ultra E4500 12-CPU server with 6 GB of RAM and data storage on two Sun T-3 partner pairs—around 240 GB of data storage in the present server configuration. The main production database includes roughly 50 GB of table space, or about 16 GB exported. Two additional Sun A1000 RAID 5 arrays are connected for replication and Oracle logs. Sun E450 platforms are used as test, development, and backup servers. Compaq servers, typically the Compaq 6500, are employed for many smaller tasks, using Compaq arrays for storage. The current environment also includes a mix of Microsoft Windows NT 4.0 and Microsoft 2000 servers. Windows platforms include one server with four instances, one with two instances, one test server with six instances, and one plot server with eight instances. A Compaq 850R is included as a domain controller and a Compaq 6500 as a Web server/support desk database engine. The current Windows Terminal Server environment consists of four Compaq 6500 servers arranged in one Citrix MetaFrame farm. A second instance is supported on a single server to support some legacy SDE 3.0 data that has already been converted to ArcGIS 8.1. Windows Terminal Servers are configured with four 500-MHz Xeon processors and 3 GB of memory, along with mirrored root disks with no other storage. A total of 90 Citrix client licenses support the production environment. The test environment consists of one Compaq M370 server. The test server has two build outs—one to mimic the production environment and one with Windows 2000 server and Citrix XP. The Reliant conversion project started with one major GIS operation consisting of 17 service centers surrounding metropolitan Houston, multiple remote gas service centers, plus a main core of users, digitizers, administrators, and management in downtown Houston. One of the GIS operational systems being replaced ran on Sun Solaris and was programmed in-house. Remote users were able to access the UNIX database using Exceed’s X-emulation package. UNIX and Novell printers were managed with JetDirect software. Users required UNIX accounts, printers, and so forth. The next major GIS operation being converted consisted of six operating divisions in Texas, Louisiana, and Mississippi. This system also included a main core of users, digitizers, and management in downtown Houston. There were also some additional digitizers and users distributed in the six operating offices across three states. The operating platform for this implementation was Windows NT 4.0. The GIS conversion project goal was to merge these two systems into one common GIS environment. There were additional challenges, as some of the existing users were located at remote sites over very slow wide area network communication links. These links ranged from 128 Kbps to 256 Kbps and a partial T-1. User needs included requirements for editing, viewing, and printing without incurring enormous infrastructure upgrade costs. The GIS vendor had some interesting ideas on how to achieve some of the major parts of our tasks. Several other vendor clients had experienced success with thin-client architectures, and Reliant was provided some best practices for implementing this technology. The vendor had established hardware configuration guidelines to support Windows Terminal Server with Citrix MetaFrame running on Microsoft Windows 4.0 Terminal Services Edition. Citrix had established a very good track record supporting GIS implementations with the Windows NT 3.51 Winframe server product, providing a good reason to believe the Windows NT 4.0 version would be even better. A local Citrix VAR provided some initial test software. Initial performance testing was conducted using a beta version of the Windows NT 4.0 version of Windows Terminal Server. The local Microsoft sales force provided beta CDs in order to set-up the original test bed. Compaq servers were used to conduct initial WTS testing in the Reliant Energy network environment. Initial WTS tests were supported by FDDI backbones and Token Ring local area networks. Since that time, much of the Reliant infrastructure has shifted to switched 100BaseT. Initial testing using traditional file-based data sources provided enough information to prove that the Citrix ICA architecture would be sending fewer packets across the wire than a traditional client/server or Microsoft’s RDP protocol. This established information supporting Citrix MetaFrame on Microsoft Terminal Server as the choice configuration for production deployment. The next deployment phase included plans within budget to ramp up support to 75 users. Compaq 6500 four-CPU 500-MHZ servers were purchased based on test results suggesting each platform could comfortably support 25 users. Three servers were purchased and configured in a farm configuration to support the initial 75 users. The current operational experience validates the initial sizing projections. Based on these results, Microsoft Terminal Servers and Client Access Licenses along with the Citrix Metaframe and load-balancing software were purchased to support the production system. In the winter of 1998, a complete WTS production configuration was established to support the huge data conversion project then underway. The data conversion plan was scheduled to go live with the first databases on May 1, 1999. Shortly after that go-live date, the central system had to be able to provide remote users access to the databases, distribute Citrix client software, set up printers on the terminal server, publish applications and, in the end, support production performance requirements. Remote GIS users were located in division offices in New Braunfels and Jacksonville, Texas, New Iberia, Louisiana, and Brandon, Missisippi. Representatives from each of those locations were brought to Houston and provided with GIS training. Representatives returned to their remote locations with CDs containing the Citrix client software to install at their home sites. Support Desk personnel followed up later with on-site visits, but in the early stages, local representatives at the remote sites supported the initial install of the software to get things going. The initial ramp-up time consisted of a few months, demonstrating positive progress toward a distributed environment that provided users the ability to update their data from remote sites. The deployed configuration supported all production databases located in Houston with centralized administration and backup. Remote sites were provided a local replicated database that would be used for printing only. (Citrix software supports printing to local printers at the remote location. This was not implemented since development tests showed that one plot over a 128-Kbps WAN segment saturated that line for over 10 minutes. Remote clients included both GIS and SAP users who shared limited WAN bandwidth, so batch plots over these lines were not recommended in the production configuration.) The remote sites databases were updated from the central database in Houston using Lakeview Technology OmniReplicator software. Remote site databases were housed on Compaq M370 single-CPU servers running Windows NT 4.0, including two 36-GB mirrored disks for the OS and database environments. The users were shown how to connect via Citrix to Houston to edit their data. Users accessed local databases using locally installed GIS software to support plotting requirements. Concurrent users supported by the Windows Terminal Server environment have continued to increase since the initial implementation. Sixty to 70 concurrent Citrix editors are supported by central WTS servers during peak work periods. (Total user count is currently 140 to 150 GIS users). Production shifts run from 6:00 am to 2:00 pm. Current usage does not show that our servers are stressed, validating that the right hardware choices were made, walking the fine line between overkill and underspend. The current environment has the capacity to handle peak loads, consistently receiving good reports from users on system response. When users experience good response time, they seem to have a more positive attitude, which increases productivity. After almost two years of production, the original servers continue to provide quality performance. Every organization strives to find ways to trim costs and improve the bottom line. Reliant Energy management recently approached the System Administration staff with some ideas about using remote users to complete some gas service line piecework. A solution was needed to support connectivity between users around Texas, and possibly using digitizer contract sources from India. The present GIS environment was using VPN software to remotely connect users working from home. A cool solution might connect remote India VPN users over the Internet, using the Citrix client, and publish special Houston-based applications for their use. This would allow GIS operations to take advantage of a less expensive labor pool. As of December 2001, over ten clients are connecting from India to Houston using this remote connection solution. Most of these clients are part-timers trained to use GIS software. These users enter gas services into the Reliant system. Other clients are posting streetlights. Shared drives have been configured on one of the Houston servers, where remote Internet clients leave screen prints of their work. QA/QC people check the work before reconciling the remote user versions with the default database and posting the changes. Remote users are required to run personal firewalls and maintain commercial anti-virus software on their Citrix client desktop. Citrix Nfuse Desktop The Windows 2000 Citrix Nfuse environment is currently used to support production operations. All of our production applications are available in this environment. Nfuse will simplify maintenance by supporting deployment of required Citrix client software to the users. Nfuse also removes the Support Desk administrative task of having to “walk” the user through client software installations and configuration support for custom parts of the client, such as connection information to new servers. Also, all client applications can be published on an existing GIS Web server simplifying the look and feel to the end users. The Nfuse icons can embed within the pages currently provided on the Web server, which once again simplifies administration. Applications can run within the frame of the Web page or as standalone seamless windows. Printing The biggest issue encountered with the Citrix software is in the printing arena. Some printers are not supported, and others have different standards in defining print-driver definitions causing major difficulties. If a user tries to print to a printer that is not defined correctly, the Citrix server can crash. GIS users hate to lose their work and don’t mind letting folks know about it. Printing solutions were deployed using aliases and other configuration tricks suggested by Citrix. Unfortunately, the Reliant environment today has a wide variety of printers and drivers. Unless each specific driver is defined properly, the Citrix server will have problems. Users have been advised not to use printers that were not compatible when printing from ArcMap via Citrix. Some early tests on Win2000 and Citrix XP indicate that some of these problems are solved with the next major release of the Citrix MetaFrame software. The Citrix XP universal print driver, however, only supports black and white at 300 dpi, and that is certainly not good enough for a GIS environment which requires support for large format to 8½” x 11”, both black and white, and color. Third-party software from various vendors promise to provide a much more stable environment. These alternatives will be tested to validate the best printing solutions. A stable printing environment will easily justify the additional software cost. The printing problem really goes beyond the crashed server. When a server crashes, the Support Desk has to get involved to help identify exactly which user caused the crash while trying to print. Stranded connections might have to be cleaned up. The users, of course, lose all work since the last save. System Administration gets involved to actually fix the print driver problem. Finally, the users are happy again—until the next system crash. Third-party print drivers promise to fix this problem. A Few Other Issues The GIS environment must include a test environment to support validation of a combination of commercial off-the-shelf (COTS) software and software written in-house. Each of these software releases must also be tested in the Citrix environment. The Citrix environment must provide a user experience that exactly mimics the GIS software running on user’s desktop. Problems in the past included lack of true-color support, transparent colors, different colors on Citrix versus standard desktops, and other related issues that have caused confusion to the users. The test platform is sometimes involved in other types of tests and not available for Citrix testing. A very simple test alternative has been to take one server out of the Citrix production farm, install the upgraded software, and have a few users production test the software to iron out any Citrix-induced kinks that may arise. Overall, the Reliant Energy experience with Citrix Metaframe and Windows Terminal Server has been a very positive one. The software is manageable and is improving from the earlier releases. Tests results have showed a production environment over a T-1 line utilizes roughly 10 Kbps of bandwidth per concurrent user. Current remote Citrix users are connecting via shared T-1, T-3, cable modem, or DSL. Windows ‘95 users experience problems. Also, network latency can cause time-out issues and an inability to refresh the icons. The new Citrix XP product and use of Nfuse for presentation promises to address some of these issues. Citrix XP uses TCP/IP instead of UDP for the refreshing of the icons and that should be a much more stable environment. Other Citrix XP improvements reside in the management and control software. XP will give administrators tools to do their job better and spend less time running the Citrix environment. The software should increase administration productivity, thereby increasing administrator productivity. There were no supported installations of Citrix Metaframe in our corporate environment when the GIS migration project started. Now that the technology is proven with the GIS implementation, our IT brethren have several major projects supported by Citrix servers encompassing several hundred licenses. In addition, the GIS team has been asked to provide Citrix application-publishing services to other departments throughout the company. Based on current operations, there is a big future for Citrix Metaframe serving applications over wireless connections. Several projects are starting up at Reliant Energy involving the use of both laptops and PDAs with wireless connections. Wireless connections typically provide user VPN access to applications running on the Citrix WTS farms. Reliant Energy is a utility with many personnel in the field, and wireless access will provide more efficient and effective customer service at a good price. Windows Terminal Server with Citrix MetaFrame supports simple lowrisk implementation of these solutions. | ||
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