[mdlug] Create an XFS file system in freespace

[Aaron Kulkis]

Jonathan Billings wrote:
> On Wed, Jul 16, 2008 at 11:38:10PM -0400, Robert Meier wrote:
>> It is analagous to a big file stored in the primary partition and
>> mounted loopback.
>> If the primary partition (or table entry) is damaged,
>> you probably lose the extended partition, 
>>
>> It differs from a loopack file,
>> in that the parent "filesystem" data is read only once,
>> at mount-time, rather than potentially at each disk access.
>> This shaves a few microseconds off each disk access,
>> at the cost of potentially more disk fragmentation.
> 
> What?  This is just confusing.  An extended partition is just an

Confusing, but Bob's analogy is valid.

> extension to the original MSDOS partition label, that lets you create
> logical partitions inside a primary partition.  The partition layout
> typically is read during boot for ALL partitions, including primary
> partitions.  Filesystem fragmentation has nothing to do with partition
> layout.
> 
> When linux boots, it reads the partition layout and maps devices to
> the start and end of the partitions, both primary and extended.  There
> is no 'cost' for using an extended partition other than that fraction
> of a second extra it takes to decode the logical partitions during
> boot.

This is true, too, but there is no conflict between your explanation
and Bob's explanation.