when disk partitioning in ubuntu, wrong informations were detected

Question

when i check disk partition in ubuntu 9.04 using #fdisk -l my friend show me like this. i have 4 hard disks, but he didn't.. but only 3. Was there anything wrong? when i installed linux and maked config? (e.g> i have miss on setting disk partition matter) and when see below result, the device sda2, sda5 start same address, end too. is there anything wrong with my disk? i have seperated 4disks.. C:,D:, G:,H: please teach me when you know about this matter. thanks.

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xe9ffe9ff

Device     Boot     Start         End      Blocks   Id  System
/dev/sda1   *           1       10199    81923436    7  HPFS/NTFS
/dev/sda2           10200       19457    74364885    f  W95 Ext'd (LBA)
/dev/sda5           10200       19457    74364853+   7  HPFS/NTFS

Disk /dev/sdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xf16cf16c

Device     Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1       10199    81923436    7  HPFS/NTFS
/dev/sdb2           10200       19457    74364885    f  W95 Ext'd (LBA)
/dev/sdb5           10200       19457    74364853+   7  HPFS/NTFS

Answer 1

Maybe the fourth "mystery disc" that you were seeing was the extended partition container for the logical partition /dev/sdb5. Your disc, when formatted with an MBR partition table, can only contain four primary partitions (sdx1, sdx2, sdx3, sdx4). If you want more partitions, one of the primary partitions can be made into an extended partition, which can contain logical partitions (sdx5, sdx6, sdx7 etc.). Hopefully that explains the discrepancy.

The reason why sdb2 and sdb5 have the same start and end is because sdb2 is the extended partition, and sdb5 (the logical partition) fills the entire extended partition's space. Hope this helps!

(I tried to interpret your question the best I could, but I can always clarify my answer if you clarify your question!)