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Re: Wheezy Installer Auto-Partition Oddity






----- Original Message -----
> From: Tom H <tomh0665@gmail.com>
> To: Debian User <debian-user@lists.debian.org>
> Cc: 
> Sent: Saturday, January 5, 2013 4:32 AM
> Subject: 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.

As I said in a previous reply, I could have misinterpreted.  I was skimming the article, not studying.


So, again I ask:  Why that 1MiB unpartitioned space before the beginning of a new partition?  Both Debian 6 and 7 installer partitioner insert it (when you choose Auto-partition; don't know whether it does with Custom) as does gparted (Discovered that when I resized three existing contiguious primary partitions [no gaps added after resizing] and added two new logical partitions [gaps added automatically] on a 7 year old 512 byte sector 160GB drive).  Got to be a reason.  I don't think it's a bug.

B


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