A second Extended Partition ?(fdisk)

Charles Curley charlescurley at charlescurley.com
Wed Jun 7 22:24:15 MDT 2006


On Wed, Jun 07, 2006 at 07:21:42PM -0600, MT Morales wrote:
> I have an unsual request to create 5 more partitions out of one which is
> currently a primary (/dev/sda3). I was thinking about destroying /dev/sda3
> and create a second extended partition. fdisk shows the following:
> 
> 
> Command (m for help): p
> 
> Disk /dev/sda: 73.2 GB, 73274490880 bytes
> 255 heads, 63 sectors/track, 8908 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>   Device Boot    Start       End    Blocks   Id  System
> /dev/sda1   *         1        15    120456   83  Linux
> /dev/sda2            16      1099   8707230   83  Linux
> /dev/sda3          1100      7251  49415940   83  Linux
> /dev/sda4          7252      8908  13309852+   f  Win95 Ext'd (LBA)
> /dev/sda5          7252      7888   5116671   83  Linux
> /dev/sda6          7889      8398   4096543+  82  Linux swap
> /dev/sda7          8399      8908   4096543+  83  Linux

Try instead: fdisk -l /dev/sda

> 
> As you can see there are no sectors left on the current extended one, and I
> can only destroy /dev/sda3 to create 5 logical ones, is this even possible?
> i.e. Is it possible to create a second extended partition out of a primary?
> Is the number of extended partitions limited to one under fdisk?

To get five logical partitions, you will need to create two more
extended partitions, as an extended partition holds at most four
logical partitions (unless that's changed since I was doing this sort
of thing. Your present extended partition has a place in its table,
but no room for it within the extended partition.

> 
> I didn't see any obvious options under fdisk to create a second extended
> partition.

You should only get that option if you are creating partitions one
through four.

> 
> Again, the only cylinders I can use for these 5 new partitions are the ones
> used by /dev/sda3. All others are already in use. There is already one
> extended partition and it's fully utilized.
> 
> Any ideas or suggestion on how to go about creating  5 additional partitions
> from cylinders: 1100 to 7251? or I'm just simply screwed?

Try:

* Build yourself a bootable CD with finnix.

* Back everything up. Everything.

* Verify the integrity of your backups.

* Delete every partition you have except sda1.

* Create three new extended partitions, numbered two through four.

* Create new logical partitions to your heart's content.

* Create file systems as needed.

* Restore data.

* Edit /etc/fstab, particularly with regard to the old sda2 and 3
  partitions. sda5, 6 and 7 will now show up in the first extended
  parttion, formerly sda2. sda2 and 3 will disappear; you'll have to
  re-assign those to sda8 and 9.

Or look into LVM, which will also require massive backup and similar
steps. Do not get rid of your boot partition or put it into a logical
volume; some kernels don't have LVM drivers until after the initrd is
mounted.

-- 

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