HP NetServer LXr Pro8 Server Controllers and Mass Storage Devices - Page 2

ZKLWHýSDSHU +3ý 1HW6HUYHUý $FFHVVRULHV By the time you've read this white paper, many of your questions about storage and controllers will have been addressed. Then the decisions that you make and the configurations that you select, as you evaluate server system choices, will meet your needs now and in the future. If you have additional questions on related topics, there are many HP NetServer white papers and technology briefs that may be of interest to you as well. A detailed listing of these references and their URLs are included at the end of this paper. A Closer Look Purpose Mass storage is the lifeblood of a server system. Selection of storage components impacts both performance and availability of the server system (see Figure 1). Storage provides the capacity to keep programs, applications, data, and other files that the system and the users require. Storage is also one of the ways to Form/Function Types Capacity Access speeds Internal or External improve and extend a server system's availability. Depending upon the system's needs for access, a variety of storage Availability Improvements Back-up Hot Swap & Hot Spare Array, RAID, Duplexing Fibre Channel solutions provide redundancy for the data and failover to alternative means of running applications should a failure occur Performance Improvements SCSI Fast and Wide, Wide Ultra 2 Increased Revolutions per Minute (RPMs) IO 2 within a server system. Other aspects of storage also affect the performance of a server system. Because mass storage is the part of a server architecture entrusted with safeguarding important data and Figure 1. Analysis of Aspects of Storage applications, selection of the appropriate mass storage components is a primary issue. Types of Storage Devices There are several categories of mass storage devices that are available for configuration in a server system. Hard disk drives come in a variety of capacities and rotation speeds and can be used internally or externally to the CPU system. They can be either fixed or hot swappable. Hot swappable drives, unlike fixed drives, can be removed and replaced without shutting the system down, thus improving overall system availability. Tape backup drives are segmented into three basic technologies: Quarter-Inch Cartridges (QIC)/Travan, Digital Data Storage (DDS) or Digital Audio Tape (DAT) and Digital Linear Tape (DLT). The performance of the disk drives depends upon the seek time, platter rotation speed, track density, and size of the disk cache buffer. The performance of the tape drives is a function of the type of device, device capacity, and data transfer rate. The capacity of both types of devices enhances the function of the server system. Small server systems currently require mass storage devices in the 9 GB range while large enterprise systems can require a terabyte or more of storage in a large arrayed set of drives. 2