Chapter 4 notes Devices that store non volatile info and organize info into individual files: USB memory keys, recordable optical disks, solid state disks (SSD), battery backed RAM, and electromechanical hard disk drives. Common disk interface types : SAS, SATA, IDE, SCSI. These apply limits for how disk hardware connects to the computer. Disk storage: any device capable of storing files for a long period of time. Internal Disk: types non removable fixed disks attached to these internal interfaces and provide a suitable location to store operating system files required to start the omputer.
The firmware built in to the computer is designed to recognized supported internal disk storage and boot from at least one of the installed internal disks. External disks: External interfaces are used to connect removable portable disk storage. Typical external disk interface types include IJSB, eSATA, SCSI, and FireWire. Is useful for expanding a computers bulk file storage to contain application and user file data. but it is not suitable for operating system files that are essential and must always be present.
Virtual Hard disk (VHD): publicly available from Microsoft, All file ata stored in a VHD is actually stored in a single file on the file system of a real disk drive. A VHD may contain thousands of individual files from the user’s perspective, but it still only appears as one physical file on the real disk drive. Only windows 7 ultimate and enterprise can natively boot from a (VHD). Logical Drives: appears to windows 7 as one disk drive. Internal, external and VHD can all be logical drives. Multiple physical drives can be grouped together to appear as one drive. reasons for doing this. Can have more combined space than one physical drive can have. And adds fault tolerance that allows for a physical drive to fail without losing access to the logical drive. Redundant array of inexpensive disks (RAID) software used to combine disks into logical drives. Instead of using operating system software to combine space from multiple drives, multiple disks can be connected to an advanced hardware based RAID disk controller. Found in more high end business comps. Not all comps have this option instead would have to use os software.
Physical drives are managed by the disk hardware controller directly and management operations are done with he management software that comes with 3rd party hardware. Since RAID disk controllers implement raid without windows 7 it is much faster than using the operating system. They can also implement RAID modes that windows cant such as RAID 5. Disadvantages of not using windows 7 are increased hardware cost, compatibility issues with device drivers and having to learn 3rd party management tools. Windows organizes data on disk drives by using one of the two basic partition styles.
Master boot record (MBR) bios firmware responsible for initializing the computer. Finds and loads the OS after boot hardware components are tested and nitialized by the BIOS Power On Self Test (POST). The MBR disk partition style defines where the BIOS examines the disk drive to determine where data is stored on the disk and the types of data it contains. MBR is still common because the startup routines for most 32 and 64 bit comps are based on it. BIOS looks for the first hard disk it ands and loads a small program on the first block of space called the boot loaded on the computer.
MBR includes boot sector and data table that identifies how partitions of space on the disk are used to store files. MBR is limited to organizing partitions on a Single drive up to 2 TB’S of space. GUID PARTITION TABLE (GPT): Extensible Firmware Interface (EFI) made to replace old BIOS standard. (UEFI) same as EFI but not made by intel. EFI/UEFI like BIOS controls the startup of the comp and loads the OS. Very few win7 comps have firmware to run EFI/UEFI. The partitions of a (GPT) disk are identified with a unique coded label called a GLOBAL Y UNIQUE IDENTIFIER (GUID).
The main advantage of using this over the (MBR) is it supports drives larger than 2 TB’s. only 64 bit windows 7 can boot from a disk drive using (GPT) partition style. BIOS can only boot from MBR. Once a partition style is selected and pplied to drive the empty space can be organized using 2 different methods. BASIC DISK STORAGE: a hard disk using this is a basic disk. A new hard disk is initially a basic disk. All versions of windows can interpret basic disks. Partition table: data structure in the MBR uses to identify reserved areas of disk space for hard disks formatted for x86 comps.
Holds a max of 4 entries. Either 4 primary partitions or 3 primary and one extended. 3 partition types on a basic disk. Primary, Extended and Logical Partitions. Primary: only type designed to store files from the OS. Basic MBR disk usually has one but could have a max of 4. The 4th on a MBR style disk will automatically become extended that will turn into logical drives. A (GPT) style disk can have a max of 128 primary partitions. The primary partition marked as active and capable of starting the OS is called the Active partition typically found in MBR since most GPT are not commonly encountered as boot disks.
If a comp has multiple basic disks each will have a basic disk. Each primary partition is represented by the OS with a drive letter. Extended partitions: MBR disk can only have one extended partition. GPT disks don’t support or use extended partitions. They don’t have drive etters. There only purpose is to reserve space and hold logical partitions. Logical Partitions: can only be created using free space inside extended partition. WIN7 refers to them as logical drives in disk administration utilities. Can only be created if extended partition has free space. Can be formatted using a file system to store files.
Drive letters can be assigned to logical partition file systems. An extended partition can only have as many logical partitions as number of free drive letters. After letters a-z are used logical partitions can no longer be properly formatted with a file system. Dynamic Disk Storage: both MBT and GPT can use this. First introduced in windows 2000. WIN7 ultimate, enterprise and professional can use this. On dynamic disks blocks of space are called Volumes instead of partitions. The dynamic disks volume database stores info about all volumes available on the computer.
Each volume is represented by a drive letter or a folder path called a mount point. Not appropriate for removable disk storage because the membership tracked for all dynamic disks in the computer. If it was removed it could impact the remaining disks. A dynamic volume must be aware of other dynamic volumes because some types of dynamic olumes interact with each other. This can increase file system capacity or provide fault tolerance through the OS. Dynamic Disks support 5 volume types (Simple, Spanned, Striped, Mirrored, RAID 5) Simple: exists on a single dynamic disk.
Can consist of one or more blocks of space from the same disk. Do not have to be data loss. Spanned: exists on 2 or more dynamic disks. Blocks of space from multiple disks are linked together to form a spanned volume. The blocks can be any size. Not fault tolerant. A failure of any linked block of space will lost entire spanned volume. Striped: minimum of 2 disks max of 32 disks. Blocks from multiple disks are linked together to form one striped volume. OS presents total of all linked blocks as one volume. Differes from spanned in how a file is written to disks.
Striped volume is a RAID O solution. When a file is saved toa striped volume its broken into smaller blocks of date. Usually 64k. the first block of data will be stored on the first disk and the next block or part is stored on the 2nd physical disk. The process continues with each physical disk, when the last disk is reached the process repeats. Results in performance increase when reading and writing data because its spread across ultiple disks. All blocks of a striped volume must be the same size. Not fault tolerant a failure would result in loss of entire striped volume.
Mirrored: can only be created with 2 dynamic disks. RAID 1 solution. Fault tolerant. Writes two identical copies of the data on the two disks. A failure to a common hardware component such as a disk controller can result in loss of mirrored volume. If each disk is placed on its own interface controller the disks would be relatively independent. Which would increase reliability. The fully redundant form of mirrored disks is a duplexed mirror. RAIDS: needs 3 or more dynamic disks. Similar to striped volume. Will stripe data and error correcting info about the data across the dynamic disks. Fault tolerant.
Makes the striped fixed blocks and calculates error correcting info about the data. Can be used to detect and repair faults. Its written so the failure of any disk allows the OS to calculate the missing data. This is possible through the spread of the error correcting data. If more than one disk fails then the volume fails. All blocks must be the same size. If 4 20gb drives, 20gb would be error correcting data. If ten 20 gb drives 10 gbs would be ECD. Disk Management Console: is a MMC snap in, part of the comp anagement utility. Allows admins to observe and make changes to comps disk confg.
DISKPART: command line tool that allows disk and volume operations to be performed from a text based screen interactively or from scripted file. Driven by sequence of commands. Preparing Hard Disks. Must complete 3 tasks before disks can store data. Scan for new hardware changes: the hardware used to connect the computer to the hard disk must be working properly. Device manager utility is used first to detect device driver issues and trigger a manual scan. Scan for disks: once first step is complete the hard disks should be visible. The OS may not see the new disks immediately.
Initializing new disks: when a new hard disk is installed on the comp it cant be used until its initialized with a fundamental structure to identify the disk and prepare it to hold data. Its called disk initialization. Should be auto but disk management console can trigger it manually. The disk cleanup utility can recover disk space. Not typically used unless necessary. The check now button on the tools tab of a local disk properties page can be used to repair corrupt data. And to report bad sectors. Defragmentation: used to group files that should be together but are pread to different parts of the disk.
This has a significant impact on the performance of the comp . Win7 runs this automatically. Can be triggered manually in the tools tab. When moving a disk from one comp to another the dynamic disk comps current dynamic disk database with the disk management console. This will update the database. The disk management console will report its status as a foreign disk. You must right click the disk in graphical portion of disk management and select import foreign disk to start import process. If your dealing with a striped or spanned or raid 5 volume all disks must be moved at the same time.
Conversions between basic and dynamic disk storage can be changed in disk management console. Required backup operator or admin permission. Basic to dynamic all partitions are converted to simple volumes. Dynamic to basic all volumes are destroyed. A backup is needed to preserve files. Before partitions or volumes can store files they must be formatted with either a FAT or NTFS file system. Partitions and volumes can be created by using the disk management snap in. shrinking or extending a volume or partition must be done with no file system or NTFS. VHDs can be created using the disk management snap in.
