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Re: Free space after partitioning



On 03/21/2012 02:18 PM, David Lehman wrote:
> On Wed, 2012-03-21 at 13:55 +0100, Jan Safranek wrote:
>>
>>   start: 110592  end: 112454  length: 1863
>> This is a free space between two logical partitions.
>> -> Again, why is the free region here? And there are 186 'hidden'
>> sectors between this free space end and start of the next logical partition.
> 
> We are somewhat more liberal with rounding start sector up for logical
> partitions, basically because parted is more aggressive in aligning
> start of logical partitions than it is with normal partitions. Also, we
> need to account for at least one sector of metadata before each logical
> partition. In some unfortunate cases this bump to the next MB boundary
> can amount to 2047 520-byte sectors. Again, parted is so aggressive with
> this that we had to do the same in order to ensure that parted
> magic/fixups do not cause unwanted surprises when the partitions are
> added to disk.

Please correct me if I am wrong - I understand it as the logical
partition metadata is at sector 112455 (=end of the free space
before+1), then there are 185 unused sectors because of alignment and
the usable data on a partition starts at sector 112640, as reported by
fdisk and storage.partitions. Nothing can ever touch these 186 sectors,
because it might overwrite the metadata.

>> If the alignment to cylinder boundary is cause of these weird numbers,
>> can I turn the alignment off in pyanaconda.storage? The numbers
>> reported by disks are completely artificial anyway these days.
> 
> We turn off cylinder alignment already.

What alignment is used then? Why the partitions don't follow each other?

Jan

>> /dev/sda6           90112      110591       10240   83  Linux
>> /dev/sda7          112640      133119       10240   83  Linux


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