[Pkg-kde-extras] Bug#759610: partitionmanager: partition alignment attribute missing from 'new partition' dialog

[Nick Boyce]

Package: partitionmanager
Version: 1.0.2-1
Severity: important
Tags: upstream

KDE Partition Manager 1.0.2 lacks a feature which it seems is needed with
modern large hard drives - specifically the ability to specify partition
alignment when creating new partitions.  More accurately, the feature is
needed when creating partitions on drives with 4KB physical sectors but
which still report a logical sector size of 512 bytes (so-called
first-generation "advanced format" drives) which is a feature of most modern
drives over about 1TB in size.

On such drives, if a partition is created starting at a logical sector which
is itself not at the beginning of a 4KB physical sector then disk transfers
to/from such a partition may require 2 physical sectors to be transferred
when 1 would have otherwise been sufficient, depending on filesystem cluster
size, access pattern (sequential/random) and transfer direction
(read/write), potentially resulting in serious performance problems. 
See [1] [2] [3] [4] [5].

The situation is complex, and I may not have understood it completely :-)

It is compounded by an apparent difference of opinion among drive
manufacturers as to whether sector numbering should begin at 0 (traditional)
or 1 (easier for 4K-drive firmware ?) - see the LKML thread at [6].

At any rate the general advice seems to be that if partitions are aligned to
MiB boundaries on advanced format drives then the performance problems will
be avoided.  This means the first partition on the drive will start at
sector 2048, rather than the traditional sector 63 - which will be fine
unless the drive needs to be shared (dual-booted) with a Windows<=XP
installation (in which case I haven't been able to figure out what is
recommended).

Since at least 2012, GParted has had a partition alignment widget (a
dropdown) on the 'new partition' dialog, offering a choice of cylinder, MiB,
or 'none' for the alignment attribute (I assume 'none' means "logical sector
alignment").  Unless partitionmanager is somehow automagically detecting the
need for 4KiB-style alignment and silently doing the Right Thing, then I
suggest it needs enhancing to offer a similar alignment choice.

I note there is a new upstream partitionmanager version 1.1.0, at a new
homepage [7], where it is stated the changes include "support for GPT
partition tables, and some nice GUI improvements in the area of partition
widget design" (paraphrasing), but there are no screen shots, and I'm still
attempting to understand the source code to see whether or not partition
alignment issues are addressed.  If the new version *does* address the
problem then bug 754580 filed against package pkg-kde-extras by Colin Watson
[8] (a request for version 1.1.0 to be packaged) will probably be sufficient
for Jessie+ releases.

[1] http://hothardware.com/Reviews/WDs-1TB-Caviar-Green-w-Advanced-Format-Windows-XP-Users-Pay-Attention/?page=2
[2] http://en.wikipedia.org/wiki/4_KB_sector_alignment#512e
[3] http://johannes-bauer.com/linux/wdc/?menuid=3
[4] http://www.ibm.com/developerworks/library/l-4kb-sector-disks/
[5] https://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues
[6] https://lkml.org/lkml/2009/2/25/444
[7] https://stikonas.eu/wordpress/?p=8
[8] https://bugs.debian.org/754580

Sorry for the length of this bug report - it seemed helpful to try to give
a full statement of the problem.


-- System Information:
Debian Release: 7.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 3.2.0-4-686-pae (SMP w/2 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages partitionmanager depends on:
ii  kdebase-runtime    4:4.8.4-2
ii  libblkid1          2.20.1-5.3
ii  libc6              2.13-38+deb7u3
ii  libgcc1            1:4.7.2-5
ii  libkdecore5        4:4.8.4-4+deb7u1
ii  libkdeui5          4:4.8.4-4+deb7u1
ii  libkio5            4:4.8.4-4+deb7u1
ii  libparted0debian1  2.3-12
ii  libqtcore4         4:4.8.2+dfsg-11
ii  libqtgui4          4:4.8.2+dfsg-11
ii  libstdc++6         4.7.2-5
ii  libuuid1           2.20.1-5.3

partitionmanager recommends no packages.

Versions of packages partitionmanager suggests:
ii  dosfstools     3.0.13-1
pn  hfsplus        <none>
pn  hfsutils       <none>
pn  jfsutils       <none>
pn  ntfsprogs      <none>
pn  reiser4progs   <none>
pn  reiserfsprogs  <none>
pn  xfsprogs       <none>

-- no debconf information