how not to initialize HD

[JB]

Gregory Hosler <ghosler <at> redhat.com> writes:

> ...
Hi,
FYI. This is from the dev team member.

From: Karel Zak <kzak at ...>
Subject: Re: cfdisk - logical partition
Newsgroups: gmane.linux.utilities.util-linux-ng
Date: 2010-08-06 13:18:37 GMT (35 minutes ago)

On Fri, Aug 06, 2010 at 01:26:27PM +0200, J B wrote:
> Example 1.
> ==========
> The last item (Free space) is "logical"
> 
>    Logical   192425984*  192426569      0         586*Free Space
> None
> 
> but clearly outside of extended  partition's range.

 This is feature. The free space around extended partition is always
 marked as logical if the number of all partitions is greater than 4
 (it means you cannot create a primary partition).

 Don't forget that cfdisk allows to create logical or primary
 partitions only. The extended partition is created/modified
 automatically for all logical partitions. The extended partition is
 completely hidden in the default output (interactive mode).

> 4 Primary   105076736*  192425983*     0    87349248*Extended (05)
> None
> 
> Should it be "None" like the Unusable partition between 3 and 2 ?

 I don't think so.

> Is that space mapped ("logical") or not ?

 cfdisk is able to use the free space for logical partitions only.
 From partition table point of view the space is invisible.

> Will an installer (e.g. anaconda which uses parted) know about it ?

 I don't know (try to use parted, you will see) ... it depends on
 libparted. I think that smart partitioning tool should be able to
 detect gaps in layout and reuse the free space.

> Example 2.
> ==========
> One more "rule to follow" with regard to partitions:
> http://www.lissot.net/partition/partition-03.html
> ...
> Unlike primary partitions, logical partitions must be contiguous.
> Each logical partition contains a pointer to the next logical partition, ...
> 
> Between partitions 2 and 4 there is a free space marked as "logical".
> 
>    Logical   219463964*  219463964      0           1*Free Space
> None
> 
> It is clearly outside of the Extended partition range.

 that's the same situation like in your Example 1.

> How comes it is called "logical" if it violates the rule of contiguousness ?

 No, cfdisk will update the first sector of the extended partition if
 you create a logical partition from the free space. The final ext
 partition will be contiguous.

> # cfdisk -Ps
> Partition Table for /dev/sda
> 
>                First       Last
>  # Type       Sector      Sector   Offset    Length   Filesystem Type (ID)
> Flag
> -- ------- ----------- ----------- ------ ----------- -------------------- ----
>  1 Primary           0      128519     63      128520 Dell Utility (DE)
> None
>  2 Primary      128520   219463963*     0   219335444*HPFS/NTFS (07)
> Boot
>    Logical   219463964*  219463964      0           1*Free Space
> None
>  4 Primary   219463965   615401954      0   395937990 W95 Ext'd (LBA) (0F)
> None
>  5 Logical   219463965   223672994     63     4209030 Linux swap / So (82)
> None
>  6 Logical   223672995   265618709     63    41945715 Linux (83)
> Boot
>  7 Logical   265618710   615401954     63   349783245 Linux (83)
> None
>  3 Primary   615401955   625137344      0     9735390 CP/M / CTOS / . (DB)
> None

> Example 3.
> ==========
> This example is by Michael Schwendt <mschwendt <at> gmail.com> .
> These are his comments.
> 
> You might want to examine the cfdisk source code to find out. cfdisk does
> not claim it would be a valid partition. It just prints a partition type
> for the free space, and that already could be a bug. Happens here, too:
> 
>                First       Last
>  # Type       Sector      Sector   Offset    Length   Filesystem Type (ID) Flag
> -- ------- ----------- ----------- ------ ----------- -------------------- ----
>  1 Primary           0      390625*     1#     390626*Linux
(83)           Boot
>  2 Primary      390626*     781250*     0      390625*Linux
(83)           None
>  3 Primary      781251*   39062500*     0    38281250*Linux
(83)           None
>    Logical    39062501*   39070079      0        7579*Free
Space           None

 this is correct, you cannot create a primary partition (all positions
 are used) and the space  is possible to add to the existing extended
 partition (part 4.)

>  4 Primary    39070080   976768064      0   937697985 W95 Ext'd (LBA) (0F) None
>  5 Logical    39070080    78124094     63    39054015 Linux
(83)           None
>  6 Logical    78124095   117194174     63    39070080 Linux
(83)           None
>  7 Logical   117194175   156248189     63    39054015 Linux (83)           None
>  8 Logical   156248190   195318269     63    39070080 Linux (83)           None
>  9 Logical   195318270   203125859     63     7807590 Linux swap / So (82) None
> 10 Logical   203125860   976768064     63   773642205 Linux LVM
> (8E)       None

    Karel

-- 
 Karel Zak  <kzak at ...>
 http://karelzak.blogspot.com
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JB