All-in-1 / A+ Certification Exm Gde, 6th Ed. / Meyers / 6311-3 CHAPTER Implementing Hard Drives 10 In this chapter, you will learn how to • Explain the partitions available in Windows • Discuss the formatting options • Partition and format hard drives • Maintain and troubleshoot a hard drive From the standpoint of your PC, a new hard drive successfully installed is nothing more than a huge pile of sectors. CMOS sees the drive; it shows up in your autodetect screen and BIOS knows how to talk to the drive; but as far as an operating system is concerned, that drive is unreadable. Your operating system must organize that big pile of sectors so you can create two things: folders and files. This chapter covers that process. Historical/Conceptual After you’ve successfully installed a hard drive, you must perform two more steps to translate a drive’s geometry and circuits into something usable to the system: partition- ing and formatting. Partitioning is the process of electronically subdividing the physical hard drive into groups of cylinders called partitions (or volumes). A hard drive must have at least one partition, and you can create multiple partitions on a single hard drive if you wish. In Windows, each of these partitions typically is assigned a drive letter such as C: or D:. After partitioning, you must format the drive. This step installs a file system onto the drive that organizes each partition in such a way that the operating system can store files and folders on the drive. Several different types of file systems are used in the Windows world. This chapter will go through them after covering partitioning. The process of partitioning and formatting a drive is one of the few areas remaining on the software side of PC assembly that requires you to perform a series of fairly com- plex manual steps. The CompTIA A+ certification exams test your knowledge of what these processes do to make the drive work, as well as the steps needed to partition and format hard drives in Windows 2000/XP. This chapter continues the exploration of hard drive installation by explaining par- titioning and formatting and then going through the process of partitioning and for- matting hard drives. The chapter wraps with a discussion on hard drive maintenance and troubleshooting issues. 343 cch10.inddh10.indd 334343 111/26/20061/26/2006 110:55:230:55:23 AAMM All-in-1 / A+ Certification Exm Gde, 6th Ed. / Meyers / 6311-3 CompTIA A+ Certification All-in-One Exam Guide 344 Hard Drive Partitions Partitions provide tremendous flexibility in hard drive organization. Partitions enable you to organize a drive in a way that suits your personal taste. For example, I partitioned my 500-GB hard drive into a 150-GB partition, where I store Windows XP and all my programs, and a 350-GB partition, where I store all my personal data. This is a matter of personal choice—in my case, it makes backups simpler because the data is stored in one partition, and that partition alone can be backed up without including the applications. Partitioning enables a single hard drive to store more than one operating system (OS). One OS could be stored in one partition and another OS stored in a second, for example. Granted, most people use only one OS, but if you want to choose to boot Windows or Linux, partitions are the key to enabling you to do so. Windows 2000 and XP support two different partitioning methods: the older but more universal master boot record (MBR) partitioning scheme and the newer (but pro- prietary to Microsoft) dynamic storage partitioning scheme. Microsoft calls a hard drive that uses the MBR partitioning scheme a basic disk and a drive using the dynamic storage partitioning scheme a dynamic disk. A single Windows system with two hard drives may have one of the drives partitioned as a basic disk and the other as a dynamic disk, and the system will run perfectly well. The bottom line? You get to learn about two totally differ- ent types of partitioning! Yay! Given that basic disks are much older, we’ll start there. Basic Disks Basic disk partitioning creates two very small data structures on a drive, the master boot record (MBR) and a partition table, and stores them on the first sector of the hard drive— called the boot sector. The MBR is nothing more than a tiny bit of code that takes control of the boot process from the system BIOS. When the computer boots to a hard drive, BIOS automatically looks for MBR code on the boot sector. The MBR has only one job: to look in the partition table for a partition with a valid operating system (Figure 10-1). Figure 10-1 Functions of the MBR and partition table cch10.inddh10.indd 334444 111/26/20061/26/2006 110:55:350:55:35 AAMM All-in-1 / A+ Certification Exm Gde, 6th Ed. / Meyers / 6311-3 Chapter 10: Implementing Hard Drives 345 NNOTEOTE Only one MBR and one partition table exist per basic disk. All basic disk partition tables support up to four partitions. The partition table sup- ports two types of partitions: primary partitions and extended partitions. Primary partitions are designed to support bootable operating systems. Extended partitions are not bootable. A single basic disk may have up to three primary partitions and one extended partition. If you do not have an extended partition, you may have up to four primary partitions. Each partition must have some unique identifier to enable users to recognize it as an individual partition. Microsoft operating systems (DOS and Windows) traditionally assign primary partitions a drive letter from C: to Z:. Extended partitions do not get drive letters. After you create an extended partition, you must create logical drives within that extended partition. A logical drive traditionally gets a drive letter from D: to Z:. (The drive letter C: is always reserved for the first primary partition in a Windows PC.) Windows 2000 and Windows XP partitions are not limited to drive letters. With the exception of the partition that stores the boot files for Windows (which will always be C:), any other primary partitions or logical drives may get either a drive letter or a folder on a primary partition. You’ll see how all of this works later in this chapter. If a primary partition is a bootable partition, then why does a basic drive’s partition table support up to four primary partitions? Remember when I said that partitioning allows multiple operating systems? This is how it works! You can install up to four dif- ferent operating systems, each OS installed on its own primary partition, and boot to your choice each time you fire up the computer. Every primary partition on a single drive has a special setting called active stored in the partition table. This setting is either on or off on each primary partition. At boot, the MBR uses the active setting in the partition table to determine which primary partition to choose to try to load an OS. Only one partition at a time can be the active partition, because you can run only one OS at a time (see Figure 10-2). Figure 10-2 The MBR checks the partition table to find the active partition. cch10.inddh10.indd 334545 111/26/20061/26/2006 110:55:360:55:36 AAMM All-in-1 / A+ Certification Exm Gde, 6th Ed. / Meyers / 6311-3 CompTIA A+ Certification All-in-One Exam Guide 346 The boot sector at the beginning of the hard drive isn’t the only special sector on a hard drive. The first sector of the first cylinder of each partition also has a special sector called the volume boot sector. While the “main” boot sector defines the partitions, the volume boot sector stores information important to its partition, such as the location of the OS boot files. Figure 10-3 shows a hard drive with two partitions. The first parti- tion’s volume boot sector contains information about the size of the partition and the code pointing to the boot files on this partition. The second volume boot sector con- tains information about the size of the partition. Figure 10-3 Volume boot sector NNOTEOTE Every partition on a hard drive has a volume boot sector. Primary Partitions If you want to boot an operating system from a hard drive, that hard drive must have a primary partition. The MBR checks the partition table for the active primary partition (see Figure 10-4). In Windows 2000/XP, the primary partition is C:, and that cannot be changed. cch10.inddh10.indd 334646 111/26/20061/26/2006 110:55:360:55:36 AAMM All-in-1 / A+ Certification Exm Gde, 6th Ed. / Meyers / 6311-3 Chapter 10: Implementing Hard Drives 347 Figure 10-4 The MBR checks the partition table to find a primary partition. NNOTEOTE Don’t confuse primary partition with primary controller. The latter, as you’ll recall from Chapter 9, refers to the first PATA drive controller on a motherboard. Even though hard drives support up to four primary partitions, you almost never see four partitions used in the Windows world. Both Windows 2000 and Windows XP support up to four primary partitions on one drive, but how many people (other than nerdy CompTIA A+ people like you and me) really want to boot up more than one OS? We use a number of terms for this function, but dual-boot and multiboot are the most common.