Run -> diskmgmt.msc -> enter (to view the partions of your disks)
Types of Hard Disk:-
a) Basic Disk:
- Primary partition
- Extended partition
- Logical drives
b) Dynamic Disk:
- Simple volume ( One Dynamic Disk )
- Spanned volume ( 2-32 D.D )
- Stripped volume ( 2-32 D.D )
- Mirrored volume ( Only two D.D )
- Raid-5 volume ( 3-32 D.D )
Note: Mirrored volume and Raid-5 volume are server based volume.
A basic disk uses primary partitions, extended partitions, and logical drives to organize data. A formatted partition is also called a volume (the terms volume and partition are often used interchangeably). In this version of Windows, basic disks can have either four primary partitions or three primaries and one extended partition. The extended partition can contain an unlimited number of logical drives. The partitions on a basic disk cannot share or split data with other partitions. Each partition on a basic disk is a separate entity on the disk.
A dynamic disk can contain an unlimited number of dynamic volumes that function like the primary partitions used on basic disks. The main difference between basic disks and dynamic disks is that dynamic disks are able to split or share data among two or more dynamic hard disks on a computer. For example, a single dynamic volume may actually be made up of storage space on two separate hard disks. Also, dynamic disks can duplicate data among two or more hard disks to guard against the chance of a single disk failure. This capability requires more hard disks, but improves reliability.D.D has a database of 1MB size therefore we can create multiple partitions.Win-2000 and onwards O.Ss support D.D while Win-95, Win-98 and Win-NT do not.
Administration of Hard Disks:-
RUN -> cmd -> enter Diskpro > list disk (to see all H/Ds)
Note: Basic to dynamic conversion can be done without losing data and without disturbing partition structure but dynamic to basic conversion causes loss of data and disturb partition structure. If we want to convert D.D back to B.D then we have to delete all volumes. By default H/D is in Basic disk.
Partition table:-A basic disk has a partition table with size of* 64 bytes. One partition description consumes 16 bytes therefore maximum 4 partitions are possible to be created on one basic hard disk. These 4 partitions can either be primary partition or extended partition. Partitions are those which have entry in partition table, which are four.
Primary partition: – A type of partition created on basic disks that can host an operating system and functions as though it were a physically separate disk. It is also called a volume. Up-to-four primary partitions can be created on a basic disk. It is an “Active Mark” partition, means where boot files are present which are used to run Operating System. Active partition (Active Mark) can be only one, but Active partition must be the part of Primary partition. The 1st and the foremost task of BIOS is to pick the boot files (sector) up from active partition and place in RAM.
Extended partition: – A type of partition on a basic disk that should be used if you want to create more than four volumes. Extended partitions can contain multiple logical drives that can be formatted and have drive letters assigned to them. It has 1MB of table.
Logical Drive: – Logical drive acts like primary partitions except that they cannot be used to start an Operating System (doesn’t belong to Active Mark/Boot Files)
A hard disk needs to be partitioned and formatted before you can store data on it. Many computers are partitioned as a single partition that equals the size of the hard disk. Partitioning a hard disk into several smaller partitions is not required, but it can be useful for organizing data on your hard disk. Some users prefer to have separate partitions for the Windows Operating System files, programs, and personal data.
Simple volume:-It is like a primary partition. Only one dynamic disk is required to create Simple Volume.
Spanned volume:-Minimum 2 and maximum 32 D.Ds are required to create Spanned Volume Attachment of one disk with another. It supports to combine space of scattered disks to make one large volume.
Usage: – If we install application (anything) that required 2GB space, we have two disks but don’t have 2GB individually. And disk ‘0’ has 1GB space while disk ‘1’ has 1.5GB space. If we combine this space from both disks, then our requirement will be fulfill because we will get 2.5GB while we are required only 2GB. It doesn’t support performance improvement. It doesn’t provide fault tolerance.(if one disk fails, then the whole volume becomes damage) Note: It is the only volume in which unequal space can be merged while in case of others volumes only equal space can be specified from each disks (unequal space support)
Stripped volume:-Minimum 2 and maximum 32 D.Ds are required to create stripped volume. We can merge equal space from each disk doesn’t support unequal space allocation. It supports to improve performance, i.e. if we require 4GB space, take 2GB from each disk. PC read/write date in 64Kb block from each disk at the same time. And it doesn’t support fault tolerance as with the case of spanned volume.
Server based volumes: – Mirrored volume: – Only two D.Ds are required to create Mirrored Volume. The old name of this volume was Raid-1 volume. It supports fault tolerance means if one disk fails then we can take same data from another disk. It means that Mirrored Volume has same copy data on both disks. There is a backup of each other. Therefore 50% space will be consumed for creating mirror. E.g. if we need 100MB space then it allocates 100MB extra space (data) from another disk for redundancy.
RAID-5 volume: RAID stands for Redundant Array Independent Disk. Minimum 3 and maximum 32 D.Ds are required to create RAID-5 volume. Its ex. name was Stripe Set With Parity. No disks keep data information in its parity because if parity fails then data will also be lost while data will be in other parity of a disk. Raid means how to engage multiple disks. It provides fault tolerance. Maximum wastage of space is 33%.If we need 600MB of space then it takes 600MB from each disk .It puts data on two disks and 3rd disk will have parity bits (information).The greater number the disk, the smaller wastage of space. So, if we have three disks then formula of calculate size of raid-5 volume will be like this,
Total size of space*(n-1) where ’n’ is the total number of disks and we subtract 1 from total number of disks because 1 disk has parity information not data.
In case of 3 disks,
=> 600*(3-1) => 600*2 = 1200MB
In case of 4 disks,
600*(4-1) => 600*3 = 1800 MB
Note:- Windows-supported RAID levels are RAID-0 (Stripped volume), RAID-1 (Mirrored volume) and RAID-5 (Raid-5 volume).