Performance of DB2 Enterprise-Extended Edition on NT with Virtual Interface Architecture

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1 Performance of DB2 Enterprise-Extended Edition on NT with Virtual Interface Architecture Sivakumar Harinath 1, Robert L. Grossman 1, K. Bernhard Schiefer 2, Xun Xue 2, and Sadique Syed 2 1 Laboratory of Advanced Computing, University of Illinois at Chicago, Chicago, IL 667, USA {sharin1, grossman }@uic.edu 2 Database Technology, IBM Toronto Laboratory, 115 Eglinton Avenue EastNorth York, Ontario M3C 1H7 {schiefer, xun, Abstract. DB2 Universal Database Enterprise-Extended Edition (DB2 UDB EEE) is a parallel relational database management system using a sharednothing architecture. DB2 UDB EEE uses multiple nodes connected by an interconnect and partitions data across these nodes. The communication protocol used between nodes of DB2 UDB EEE has historically been Transmission Control Protocol (TCP) / Internet Protocol (IP) but has now been extended to include the Virtual Interface (VI) Architecture. This paper discusses a new protocol termed Virtual Interface Protocol (VIP), built on top of the primitives provided by the VI Architecture. DB2 UDB EEE with VIP on a fast interconnect has shown significant improvement in reducing the elapsed time of queries when compared with TCP/IP over fast ethernet. This paper discusses the implementation and performance results on a Transaction Processing Council s Decision (TPC-D) support database. 1 Introduction In contrast to traditional database queries, business intelligence queries are broadly concerned with extracting information from databases to facilitate decision making. These types of queries can be both compute and data intensive. Clusters of workstations are emerging as a powerful platform for performing these types of queries [3]. An important factor limiting the effectiveness of clusters has been the high latency of protocols such as TCP/IP which are commonly used to interconnect the workstations in a cluster. The Virtual Interface (VI) Architecture developed by a consortium led by Compaq, Intel, and Microsoft [2] is a specification for connecting workstations and peripherals, which reduces latency. The key idea is to move data directly from an application to the network interface controller (NIC) of the network interface hardware without going through the operating system [1]. C. Zaniolo et al. (Eds.): EDBT 2, LNCS 1777, pp , 2. Springer-Verlag Berlin Heidelberg 2

2 Performance of DB2 Enterprise-Extended Edition on NT 225 Clusters of workstations provide a natural shared-nothing architecture. With this type of architecture many operations can be performed in speeding up the overall computation. What is relevant here is that different workstations do not share a common memory but rather explicitly move data between the different memories. DB2 UDB EEE is based on this shared-nothing architecture [4, 5]. DB2 UDB EEE on Windows NT historically used TCP/IP for communication between the nodes. This paper discusses on improved performance of DB2 UDB EEE by utilizing the VI Architecture. This paper is organized as follows. Section 2 describes the partitioning strategy used by DB2 UDB EEE. Section 3 describes the VI Architecture and how we integrated the VI Architecture for DB2 UDB EEE. Section 4 describes the experimental studies on the eight node and sixteen node clusters. 2 DB2 Universal Database DB2 UDB EEE [4, 5, 6] is designed to support the very large databases that Business Intelligence applications often require. DB2 UDB EEE incorporates a highly scalable shared-nothing software architecture, which allows it to exploit symmetric multiprocessor (SMP) systems, clusters of SMP systems, MPP systems. This architecture enables DB2 UDB EEE to support very large databases by dividing the database into partitions, which can be stored and managed on separate nodes of a shared-nothing hardware platform. By searching these database partitions in parallel, elapsed times for queries can be dramatically reduced. Nodes communicate over a interconnect and operate in parallel. The individual nodes can be either uniprocessor systems or SMP systems. In either case, each system node will have its own memory and access its own disks, but will share a scalable interconnect that always ensures point to point connectivity across the system. 3 Virtual Interface (VI) Architecture The Virtual Interface (VI) Architecture [2], proposed by Compaq Computer Corporation, Intel Corporation and Microsoft Corporation, is a specification that defines industry-standard architecture for distributed messaging within a System Area Network (SAN). It is aimed at achieving low latency and high bandwidth communication between subsystems, with minimal Central Processing Unit (CPU) usage. The VI Architecture achieves this by providing direct access to the network interface hardware with appropriate hardware protection checks, there by avoiding the system-processing overhead inherent in traditional network architectures. With the introduction of the VI Architecture DB2 UDB EEE on NT can communicate in a distributed messaging environment using low-latency, high speed SANs. The new interconnect fabrics that support the VI architecture are able to provide high bandwidth for transferring many messages, low latency for fast point-to-point deliv-

3 226 Sivakumar Harinath et al. ery, and fault tolerance for ensuring messages reach their destination. The next section discusses few highlights of the experiments conducted. The full results, analysis, and detailed information on the implementation of DB2 UDB EEE on NT with VI Architecture as well as can be found in [7]. 4 Implementation and Performance Results Experiments were conducted on two cluster configurations eight nodes and sixteen node DB2 UDB EEE clusters. A 1 Gigabyte/17 query TPC-D [8] database was used in our experiments. Each node of the eight node cluster was a four way with 2 MHz Pentium Pro processors, 2 GB of main memory, and 1 Megabyte (MB) of L2 cache. Each node of the sixteen node cluster was a four way with 4 MHz Pentium II Xeon TM processors, 1 GB of main memory, and 512 Kilobytes of L2 cache. Every node in both clusters contained a GigaNet s GNX 1 card and Intel 1Mb/s Ethernet Cards. Each cluster was connected by two interconnects -- Giganet s GNX 5 switch and also by Intel Express 1/1 Stackable Hub. vs Elapsed Time (seconds) ÈÃ)DVWHU Fig 1. Elapsed time of TPC-D queries for sixteen node cluster Figure 1 and Table 1 illustrate the performance of the VIP implementation in total elapsed time of all queries with experiments run on both the 8 and 16 node clusters. VIP performed better than TCP/IP on a per cluster basis and experienced better scalability characteristics over TCP/IP when the number of nodes increases. The eight-node cluster was also used to simulate a test similar to the throughput test of the TPC-D benchmark [8]. One of the communication intensive queries (Query 17) was run as two streams, four streams and eight streams, simulating multiple users accessing the database. Fig. 2 shows the average query elapsed times of multi-stream invocations of this query. It was noticed that the VI implementation performed better as compared to TCP/IP. It was observed that VIP performs better when there is more data transfer between nodes, due either to communication intensive queries or high user loads.

4 Performance of DB2 Enterprise-Extended Edition on NT 227 vs Using 17th Query of the Sequence 5 Average Elapsed time Thousands Stream 4 Stream 2 Stream Fig 2. Elapsed time of multi-stream invocation of a communication intensive query CPU usage % CPU usage Comparison Kernel % User % Total % Fig 4. CPU activity during VIP and TCP/IP Table 1. Elapsed time comparisons for 8 and 16 nodes Interconnect/Nodes Elapsed time for Eight Nodes Elapsed time for Sixteen Nodes Gain from node increase (%) Fast Ethernet VIA Gain from VIA (%) Figure 3 presents the CPU activity during the time period this query was run. This clearly shows that the kernel CPU activity while using VIP is lower than in TCP/IP. These extra CPU cycles are utilized by the DB2 UDB EEE applications and there by results in faster completion of the queries.

5 228 Sivakumar Harinath et al. 5 Conclusions With the dramatic drop in the price of workstations and fast interconnects, clusters of workstations are a viable option for handling high performance queries on large data sets. DB2 UDB EEE on Windows NT was modified to utilize the VI Architecture with the VIP, a specialized protocol reducing the latency and CPU utilization associated with TCP/IP. Experiments were performed on a 1 TPC-D database on 8 and 16 node clusters connected by fast ethernet hub and Giganet s VI Arhcitecture supported switch. Running TCP/IP on the switch was only marginally better than running TCP/IP over the hub. On the other hand, running VIP over the switch provided speed ups over TCP/IP running over the hub of between 1% and 89%, depending upon the query and the size of the cluster. In general, data intensive queries on the larger cluster had more dramatic improvements, since the overall reduction in latency, due to the larger number of connections, was greater. In addition to reduced latency, a secondary benefit was the reduced CPU utilization of VIP compared to TCP/IP allowed the queries to complete faster since more of the CPU was available for the query. References 1. Buonandonna, P., et al.: An Implementation and Analysis of the Virtual Interface Architecture. Proceedings of the Supercomputing `98 Conference (1998) 2. Compaq, Intel and Microsoft: Virtual Interface Architecture Specification, Version 1.. Compaq (1997) 3. Grossman, R., Bailey S., Hanley, D.: Data Mining Using Light Weight Object Management in Clustered Computing Environments. Proceedings of the Seventh International Workshop on Persistent Object Stores, Morgan-Kauffmann, San Mateo (1997) IBM Corporation: DB2 Universal Database goes parallel with Enterprise and Enterprise-Extended Edition. IBM Corporation (1998) 5. IBM Corporation: IBM DB2 Universal Database on Windows NT Clusters. IBM Corporation (1998) 6. IBM Corporation: IBM DB2 Universal Database Administrator Guide, Version 5.2. IBM Corporation (1998) 7. H. Sivakumar H., et al: Improving the performance of DB2 UDB EEE with the Virtual Interface Protocol. LAC Tech Report 99-23TR, Laboratory for Advanced Computing, University of Illinois at Chicago (1999). 8. Transaction Processing Performance Council: TPC-D Benchmark Specification Version. (1998)