touch-packages team mailing list archive

[DiagonalArg <1531404@xxxxxxxxxxxxxxxxxx>]

Prompted by a chat on #ubuntu-bugs, I'll point this out:

(1) Since an MBR has a signature at the end, 0x55AA, then what we're
seeing should not be happening.  It's possible in all but 1 in 65536
cases to definitively identify that there is no partition table on the
disk.

(2) Even in that small chance that the signature is there "randomly" (on
a random filled disk), partition entries would also show up randomly.
They would not show up specifically at 181GB into the disk.

Therefore, something that we shouldn't expect is going on here.

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https://bugs.launchpad.net/bugs/1531404

Title:
  nonexistent partition in /dev, & lsblk/disk util misbehaving with
  randomized disks

Status in util-linux package in Ubuntu:
  New

Bug description:
  I have two 2T disks with no partition table and which have been filled
  with random data.  GNU parted shows nothing on this disk:

  GNU Parted 3.2
  Using /dev/sda
  Welcome to GNU Parted! Type 'help' to view a list of commands.
  (parted) print
  Error: /dev/sda: unrecognised disk label
  Model: ATA WDC WD2002FAEX-0 (scsi)
  Disk /dev/sda: 2000GB
  Sector size (logical/physical): 512B/512B
  Partition Table: unknown
  Disk Flags:

  but when I check with `lsblk`, I see one disk with partitions and the
  other without:

  Code:
  NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
  sda 8:0 0 1.8T 0 disk
  └─sda2 8:2 0 1.6T 0 part

  NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
  sdb 8:16 0 1.8T 0 disk

  and the Disks utility agrees (see: http://ibin.co/2SQv4KbH06Mz).

  Also, /dev/disk/by-id contains an entry pointing to sda and one
  pointing to sda2. So it really does think there's a second partition
  there.

  Thinking there was something wrong, I re-filled the disks with random
  data.  Now sda is properly (in the Disks utility as just an "unknown
  disk"), but sdb shows a second partition, and identically to how sda
  was showing it before (ie the Disks utility output is the same with
  181GB at the beginning and 128GB at the end).

  I am running all this from the Ubuntu Gnome 15.10 installer disk.

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