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1 Overview In this chapter, you will learn to Explain the partitions available in Windows Discuss the formatting options Partition and format a hard drive Introduction A new Hdive (HD) is nothing than a huge pile of sectors. CMOS sees the drive, it shows up in the autodetect screen and BIOS knows how to talk to drive. For operating system, It must organize that pile of sectors so one can create 2 things: folders and files. After installing a HD, 2 more steps must be performed to translate a drives geometry into something usable to the system. Partitioning and formatting. 3 Partitioning Process of electronically subdividing the physical hard drive into groups of cylinders. Called partitions or volumes A HD must have at least one partition. You can have multiple partitions on single HD. Windows assigns them names such as C: or D: Logical divisions of a hard drive. 4 Partitioning 5 Formatting After partition you must format derive. Installs a file system onto the drive that organizes each partition in such a way that operating system can store files and folders on the drive. called high level formatting. 6 Hard Drive Partitions Partitions provides flexibility in HD organization. You can organize a drive in a way that suits your taste. How? Partitioning enables a single HD to store more than one operating system . Windows 2000/XP support 2 different Partitioning methods: 1. Master Boot Record (MBR) partitioning scheme. • Older but universal • The HD is called ‘basic disk’ 2. Dynamic partitioning scheme. • Newer but proprietary to Microsoft • The HD is called ‘dynamic disk’. 7 Basic Disk Basic disk partitioning creates two very small data structures on a drive: Master Boot Record (MBR) and a Partition Table Stores them on the first sector of the HD- called the Boot Sector. MBR is a tiny bit of code that takes control of the boot process from system BIOS. When a computer boots to a HD, BIOS automatically looks for MBR code on the boot sector. 8 Basic Disk MBR looks in the partition table for a partition with a valid operating system. Only one MBR per disk Program Data 9 Basic Disk Partition table supports up to 4 partitions. Supports 2 types of partitions: primary and extended. Primary: designed to support operating systems.(bootable) Extended: not bootable A single disk may have up to 3 primary partitions and only one extended partition. If you don’t have an extended partition, you may have up to 4 primary partitions. This allows for multiple (up to 4) operating systems (called multiboot, dual boot) 10 Basic Disk Each partition must have some unique identifier to enable user to recognize it as an individual partition. Windows assign primary partitions a drive letter from C: to Z:. Extended partition do not get drive letters. After you create an extend partition you must create logical drives within that extend partition. Logical drive get a drive letter from D: to Z: C: is always reserved for first primary partition in windows PC. 11 Hard Drive Partitioning C: ? 12 Volume boot sector The first sector of the first cylinder of each partition also has a boot sector called volume boot sector. Stores information important to its partition, such as location of OS boot files and partition size. 13 Primary Partition Can be bootable Has a special setting called ‘active’ stored in the partition table. It is either on/off on each primary partition. Only one partition at a time can be the active partition because you can run only one OS at a time. At boot, the MBR uses the active setting to determine which primary partition is active to load OS from. The partition is set active when you install OS. It never actually says this in the install. Rest of chapter assume only one primary partition. 14 Boot Sector 15 Boot Sector Few system use more than one primary partition. You almost never see four partitions used in windows world. How we can change active partition? And why? 16 Extended Partition Why we have extended partition? Further divided into logical drives which get a drive letter from D: to Z: An extend partition may have as many logical drives as you wish. Cannot be bootable or Active Completely optional. What doest means? Why we try to create extended partition. 17 Partitions Primary Partition Extended Partition Primary Partition Logical Drive 1 Drive Letter = c: Drive Letter = d: Set to “Active” Stores O.S. Logical Drive 2 Drive Letter = e: Hard Disk 18 Example 2 Drives (DOS) Dual OS Master Extended Partition Primary Partition C: E: MBR Logical Drives tells layout of the disk Primary Partition D: MBR tells layout of the disk F: Slave Extended Partition G: H: Logical Drives 19 When to partition Two most common situations: when installing an OS on a new system when adding a second drive to an existing system Traditionally, once a partition is made, you can not change its size or type other than by erasing it. Third-party tools can non-destructively resize partitions (without losing the data) Windows 2000 and XP can non-destructively resize a partition to be larger but not smaller. Vista can non-destructively resize partitions any way we wish. 20 21 Hard Drive Formatting Done after partitioning Every partition needs to be formatted. Why? Formatting does two things It creates a file system – like a library’s card catalog and makes the root directory in that file system. Current file systems in Windows: FAT16 FAT32 NTFS. Root directory provides foundation upon which OS builds files and folders. 22 FAT – File Allocation Table A file is stored in many sectors (possibly one). The main job of FAT is to track which sectors are assigned to each file, which sectors are unused and which are bad. The sector number is represented in 16 bits. Therefore there are 64K sectors (2^16). 64K sectors limits partition size to 32MB (how?) 23 FAT – File Allocation Table The right column of the FAT contains information about the status of sectors. Formatting: creating FAT and testing sectors. Assign 0000 to good and open for use sectors and FFF7 to bad ones. OS must locate bad sectors (if any). This mapping of bad sectors is one of the functions of high-level formatting. Floppy disks use FAT with 12 bits. 0000 0000 0001 FFF7 0002 0000 ………. 0000 ………. 0000 FFFF 0000 24 FAT Limited Using 16-bit FAT addresses a maximum of 64 K location. The size of hard disk partition should be limited to 64 K x 512 bytes per sector (32 M). As hard drives grew in size you could use FDISK to break them up into multiple partitions. Therefore using FAT 16 with very large HD is unacceptable. Solution was clustering, allowing partition sizes up to 2 GB 25 Clustering To break the limit of 32MB in partition size with backward compatibility. Enables one to format partition larger than 32MB Idea: combining a set of contiguous sectors and treating them as a single unit (cluster) in FAT. i.e. FAT addresses a cluster instead of a sector. So, the cluster became the smallest addressable block of data stored on a drive. The size of a cluster is not fixed. 26 Clustering Number of clusters is still 64K (16 bit). So, number of sectors/cluster is determined according to partition size. (how?) The large the partition the more sector per cluster. 27 Clusters and Sectors 28 FAT16 FAT16: clustering FAT where the cluster is represented in 16 bits. Cluster sizes: 4,8,16,32 64 (max. partition is 2GB). Compute it? Hard Drives become fragmented. This mean that data for one individual file may not be in consecutive clusters Excess fragmentation slows down systems. It needs defragmentation from time to time. 29 FAT16 in Action When an API tells the OS to save a file (MOM.TXT). Windows start at beginning of FAT looking for the first open cluster. 30 FAT16 in Action Before filling 3ABC window enter the value 3ABC in 3ABB status. FAT 16 31 FAT16 in Action 32 FAT16 in Action 0000 = Good FFF7 = Bad FFFF = End of File 33 FAT and Root Directory Windows then goes to the folder storing the file and adds the file name and the cluster’s number to the folder list File folder located in different cluster. What happen if program requesting that file? 34 Fragmentation Fragmentation occurs when files are spread across drives (not contiguous) Individual files are broken into pieces that fit into a sector or cluster The pieces are stored on the hard drive but may not be stored in contiguous clusters Fragment take place all the time on FAT 16. Fragmentation slows down the system during hard drive reads and writes Programs such as Disk Defragmenter or Speed Disk can be used to defragment files, folders, or both Takes longer for system to piece together and can impact performance. 35 Disk Defragmenter 36 Disk Defragmenter 37 FAT 32 Uses 32 bits to describe each cluster Cluster size can drop to reasonable size compared to FAT16. A 2-GB volume using FAT16 would use 32-KB clusters, while the same 2-GB volume using FAT32 would use the minimum cluster size (4KB). FAT 32 support partition up to 2 terabyte. But needs de-fragmentation Remember, only DOS and Windows 3.x/95/98/Me use FAT 38 NTFS File system of choice today. NT File System (NT came from Windows NT, first OS to use it) Windows NT, 2000, XP, Vista. Uses clusters and file allocation table in a much more complex and powerful way compared to FAT16 and FAT32 this table called Master File Table (MFT). Main improvements: redundancy, security, compression, encryption, disk quotas, and cluster sizing. 39 NTFS Security: Provides file and folder access control Uses Access Control List with permissions If you’re on the list, you’re granted the specific permission Compression: Compresses data on a hard drive to allow more data to be written to the drive. (Slower). Encrypting file system: Allows files and folders to be encrypted and unreadable to anyone without the key 40 NTFS Files and folders can be encrypted or compressed Disk quotas Can control how users can use space Set on a per-drive basis Cluster sizes Can adjust cluster sizes Rare to do so 41 Divisions of a Hard Drive 42 43 Bootable Disks Any software that can boot up a system is by default OS. Bootable disk is any removable media that has a bootable OS installed Floppy, CD-ROM, USB thumb drive All Windows and Linux installation CDs are bootable 44 Install Hard Drive Connectivity CMOS Partitioning Formatting 45 46 48 49 50 51 52 53 54