Re: Wheezy Installer Auto-Partition Oddity
On Fri, Jan 4, 2013 at 1:25 PM, Patrick Bartek <bartek047@yahoo.com> wrote:
> From: Roger Leigh <rleigh@codelibre.net>
> Sent: Friday, January 4, 2013 3:02 AM
>>
>> LVM does not use unpartitioned space for anything TTBOMK. It uses
>> physical volumes (PVs) which are block devices (either partitions or
>> whole disks or RAID arrays etc.). These are entirely self-contained.
>> Internally, the PV contains its own metadata and extents which are
>> allocated to individual logical volumes within the volume group
>> containing the PV. It's simply impractical and fragile to use
>> unpartitioned space, and LVM only uses the devices (partitions) you
>> put the PVs on.
>
> That was what I read--somewhere?--in an article on LVM. It was just
> one sentence mentioned in passing and was never detailed.
>
> If using unpartitioned space is so "fragile" Why do the MBR or GPT,
> etc. use it? Seems to be a great place to "hide" data about something
> like a LVM partition that's not going to change frequently, and is
> beyond normal filesystem access. Just a thought.
The MBR, whether on msdos or gpt, is a well-defined area at the
beginning of a disk, not a random space between partitions.
There's no LVM data held off a PV, whether it's a partition or a disk.
The LVM metadata of a PV is stored in the second sector of that PV and
its LV "usable area" follows. Your article might have been referring
to this separation.
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