HP ML570 Novell NetWare 6 performance tuning guidelines for ProLiant servers - Page 5
server subsystem components and selection guidelines, disk subsystem, SCSI specifications
UPC - 808736750752
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Novell NetWare 6 performance tuning guidelines for ProLiant servers server subsystem components and selection guidelines disk subsystem SCSI specifications As stated earlier, the Ziff-Davis test suites were chosen. The decision to use the Ziff-Davis Benchmark is because it is designed to mimic real-world user applications. Original equipment manufacturers (OEMs) and personal computer (PC) magazine use the Ziff-Davis test suites in their research publications. To obtain the latest copy, go to www.zdnet.com. The IT professional or the system administrator is responsible for selecting which subsystem components provide sufficient bandwidth for optimal overall server performance. Once the server is selected, the appropriate NOS is chosen to leverage the server hardware components. For instance, if a multiprocessor (MP) server is selected, then a corresponding network operating system and applications that are MP-aware should be used. The following sections highlight examples of critical server subsystem components and how the selection you make can dramatically affect server performance. The disk subsystem consists of the disk and the controller. One of the functions of the disk subsystem is to keep the memory or cache filled with useful data. Insufficient memory leads to a low cache hit rate and slower user access time. When this occurs, performance decreases. It is a known fact that disk response time is significantly slower than memory response time. The performance of the disk subsystem can therefore be affected by the components that constitute the subsystem. There are several elements that makeup the disk subsystem (i.e., SCSI (small computer system interface), disk, controller, drivers, bus interface, etc.). The following components are crucial during the selection process: • SCSI • disk • controller • SCSI technology SCSI technology is a widely used standard for transferring data between the disk drive and the SCSI controller. Many types of SCSI technology are currently available and the one you chose can impact overall system performance. It is therefore recommended to select the type with the highest speed your disk drive and controller can support. Table 1 lists the different types of SCSI standards currently available. table 1. SCSI standard specifications SCSI standard SCSI SCSI-2 SCSI ultra SCSI ultra2 SCSI ultra3 SCSI ultra4 bus speed (MHz) 5 10 20 40 40 80 50-pin narrow (8-bit) 5 MB / s 10 MB / s 20 MB / s 40 MB / s 68-pin wide (16-bit) 20 MB / s 40 MB / s 80 MB / s 160 MB / s 320 MB / s maximum cable length 6 meters 3 meters 1.5 meters 12 meters (LVD) 12 meters (LVD) 12 meters (LVD) 5