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Old 03-27-2006, 02:26 PM   #1
eder_michael11
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i can not create all partitions i want with cfdisk -- slackware 10.0


sorry i am installing slackware 10.0 but when i want to create the 6th partition ... the space that i have free at my disk turns unusable and i cant make a new partition there

i created

swap logical 500Mb
boot primary 50Mb
usr primary 2000Mb
var primary 2000Mb
/ primary 3000Mb

free space UNUSABLE

does somebody knows why i cant create other partition?
??
 
Old 03-27-2006, 02:33 PM   #2
saikee
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You can have a maximum of 4 primary partition any hard disk if you are using on a PC operating system.

If you want more then one of the prmaries must be given up to exchange for an extended partition. Inside an extended partition you can have 60 and 11 logical partitions for an IDE and Sata respectively for Linux.

Available space is not always usable if you deviate from the above.
 
Old 03-27-2006, 02:41 PM   #3
Michael_S
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http://tldp.org/HOWTO/Partition/ May have information you need.

I can't tell what's wrong with what you have written, but this is my guess:

The Intel PC architecture supports four regular (called Primary) partitions. If you want to make more than that, you make three normal Primary Partitions and your fourth partition is an Extended Partition (which is a special type). The Extended partition can then get divided into additional Logical Partitions.

So let's say you have a 160 GB disk and you want to divide it into 5 31 GB partitions and 1 5 GB swap partition. Your partition setup would look like this:
sda1 (or hda1) 0-31GB Type ext3, NTFS, whatever (Primary)
sda2 (or hda2) 31-62GB Type ext3, NTFS, whatever (Primary)
sda3 (or hda3) 62-93GB Type ext3, NTFS, whatever (Primary)
sda4 (or hda4) 93-160 GB Type Extended (Extended)
sda5 (or hda5) 93-124 GB Type ext3, NTFS, whatever (Logical)
sda6 (or hda6) 124-155 GB Type ext3, NTFS, whatever (Logical)
sda7 (or hda7) 155-160 GB Linux Swap (Logical)

So the fourth real partition is designated Extended and gets subdivided into the last three logical ones. Make sense?

If you have more than 4 partitions on an Intel machine, the fourth partition MUST be extended.

Good luck.
 
Old 03-27-2006, 02:54 PM   #4
pixellany
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Quote:
Originally Posted by Michael_S

If you have more than 4 partitions on an Intel machine, the fourth partition MUST be extended.
This is really splitting hairs, but (I think) that any one of the first four can be extended partitions.

IF I understand correctly---each sector that has partition tables is allowed 4. If any one of them is an extended partition, then that entry is just a pointer to another set of four tables in a different sector.

The way I read it, you could start with 4 extended partitions, and then create four logicals for each--total 16

I also think that maybe extended can lead to another extended?? (Not clear on the details)
 
Old 03-27-2006, 04:58 PM   #5
Michael_S
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pixellany,
Thanks for the info, I appreciate it.
 
Old 03-27-2006, 06:36 PM   #6
saikee
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I am going to subdivide the split hair done Pixellany.

Absolutely spot. Any of the 4 primaries can be turned into an extended partition.

The way it has been documented is in PC standard the Bios reads the MBR, strips the 64 bytes after the 446th byte and assumes there are 4 primary partitions there. Each primary has 16 bytes entries. Among mang things the starting and finishing points in the disk are given in each primary partition.

The Bios knows the partition being an extended kind by its partition ID. Type f would be an extended partition created in Win95.

An extended partition has the starting position of the first logical partition and the finishing point of the last logical partition only. With that information the Bios can goto the first logical partition to read another "sub-partition table" which points to the next logical partition further down. Logical partitions are therefore always named consecutively without any omission. If a user deletes hda10 the logical partition from hda11 will automatically shifted up by one and the deleted area is a dead space.

If a user starts a logical partition from a new disk it will be automatically be hda5 and its first primary partition position hda1 will be automatically turned into an extended kind. Hda1 to hda4 are always reserved for the 4 primaries regardless if some of them are not used.

If a user doesn't know how the partitions are created then he can end up with useless dead spaces.
 
  


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