Partition tables / Output of parted

Partition tables / Output of parted

[Stefan Malte Schumacher]

Hello

I have created multiple filesystems with btrfs, in all cases directly
on the devices themself without creating partitions beforehand.  Now,
if I open the disks containing the multi-device filesystem in parted
it outputs the partion table as loop and shows one partition with
btrfs which covers the whole disk. Opening the disk with the
single-device fileystem in parted shows a partion table, type unknown
and no partition on the disk itself. 

I am unsure how to interpret this output. Two possible explanations
come to mind: a) Btrfs does create partitions, but only if a filesystem spans
multiple devices or b) the output of parted is faulty and no actual
partition is created in both cases. 

Could someone elaborate on this question or just point out where I can
find documentation on this issue?

Yours sincerely
Stefan 

Re: Partition tables / Output of parted

[Russell Coker]

On Wed, 4 Jun 2014 13:19:16 Stefan Malte Schumacher wrote:
> I have created multiple filesystems with btrfs, in all cases directly
> on the devices themself without creating partitions beforehand.

I do that sometimes, it works well.  I've done the same thing with Ext2/3 in 
the past as well, it's no big deal.

> Now,
> if I open the disks containing the multi-device filesystem in parted
> it outputs the partion table as loop and shows one partition with
> btrfs which covers the whole disk.

http://lists.alioth.debian.org/pipermail/parted-devel/2009-May/002840.html

A Google search on "Partition Table: loop" turned up the above explanation as 
the third result.

> I am unsure how to interpret this output. Two possible explanations
> come to mind: a) Btrfs does create partitions, but only if a filesystem
> spans multiple devices or b) the output of parted is faulty and no actual
> partition is created in both cases.

BTRFS doesn't create partitions.

-- 
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Re: Partition tables / Output of parted

[Mike Fleetwood]

On 4 June 2014 14:30, Russell Coker <russell@coker.com.au> wrote:
> On Wed, 4 Jun 2014 13:19:16 Stefan Malte Schumacher wrote:
>> I have created multiple filesystems with btrfs, in all cases directly
>> on the devices themself without creating partitions beforehand.
>
> I do that sometimes, it works well.  I've done the same thing with Ext2/3 in
> the past as well, it's no big deal.
>
>> Now,
>> if I open the disks containing the multi-device filesystem in parted
>> it outputs the partion table as loop and shows one partition with
>> btrfs which covers the whole disk.
>
> http://lists.alioth.debian.org/pipermail/parted-devel/2009-May/002840.html
>
> A Google search on "Partition Table: loop" turned up the above explanation as
> the third result.
>
>> I am unsure how to interpret this output. Two possible explanations
>> come to mind: a) Btrfs does create partitions, but only if a filesystem
>> spans multiple devices or b) the output of parted is faulty and no actual
>> partition is created in both cases.
>
> BTRFS doesn't create partitions.

c) Parted (libparted) is merely displaying a pretend loop partition
table as a way to represent the situation of a file system covering
the whole disk in it's view of the world where all disks have a
partition table.

Mike