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I was installing Windows 7 using the CD. I have 3 partitions already, and when creating a new partition using the DVD, it says "You cannot create a new volume in this unallocated space because the disk already contains maximum number of partitions." How can I create more partitions?

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up vote 5 down vote accepted

Create an extended partition, then you can create logical partitions. I don't know if Windows 7 will install on a logical partition though

Explanation: (from Wikipedia - Disk Partitioning)

This section describes the master boot record (MBR) partitioning scheme, as used in DOS, Microsoft Windows and Linux among others on PC compatible computer systems. For examples of partitioning schemes used in other operating systems, see the general article on partition tables.

The total data storage space of a PC hard disk can be divided into at most four primary partitions, or alternatively three primary partitions and an extended partition. These partitions are described by 16-byte entries that constitute the Partition Table, located in the master boot record.

The partition type is identified by a 1-byte code found in its partition table entry. Some of these codes (such as 0x05 and 0x0F) may be used to indicate the presence of an extended partition. Most are used by an operating system's bootloader (that examines partition tables) to decide if a partition contains a file system that can be used to mount / access for reading or writing data.

Primary partition

A primary partition contains one file system. In DOS and earlier versions of Microsoft Windows systems, the system partition was required to be the first partition. More recent Windows operating systems (Win7, XP, etc.) can be located on any partition, but the boot files (bootmgr, ntldr, etc.) must be on a primary partition. However, other factors, such as a PC's BIOS (see Boot sequence on standard PC) may also impart specific requirements as to which partition must contain the primary OS.

The partition type code for a primary partition can either correspond to a file system contained within (e.g. 0x07 means either an NTFS or an OS/2 HPFS file system) or indicate that the partition has a special use (e.g. code 0x82 usually indicates a Linux swap partition). The FAT16 and FAT32 file systems have made use of a number of partition type codes due to the limits of various DOS and Windows OS versions. Though a Linux operating system may recognize a number of different file systems (ext4, ext3, ext2, ReiserFS, etc.), they have all consistently used the same partition type code: 0x83 (Linux native file system).

Extended partition

A hard disk may contain only one extended partition; the extended partition can be subdivided into multiple logical partitions. In DOS/Windows systems, each logical partition may then be assigned an additional drive letter.

Basically, you can have 4 "real" partitions on a disk; to get more, you make up to 3 Primary partitions, then 1 "extended" partition that has multiple "logical" partitions inside of it. The extended partition does NOT get a drive letter, but the logical partitions inside of it would get letters if assigned

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i want to install ubuntu on that extra 4 th partition can i ? – Bhavesh Gangani Jan 3 '12 at 5:55
@BhaveshGangani Yup – Canadian Luke Jan 3 '12 at 5:56
how to create that extra partition ? via disk management utility provided in windows 7 ? if yes then how ? please give detailed info because i'm afraid to lost data on other drives . thanks – Bhavesh Gangani Jan 3 '12 at 5:57
ok done it. i've converted it to dynamic . thanks for your suggestion . – Bhavesh Gangani Jan 3 '12 at 7:14
@BhaveshGangani Not a problem. I'm going to do a writeup to expand on the answer as to why – Canadian Luke Jan 3 '12 at 18:08

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