[Pkg-kde-extras] Bug#759610: More info: warning from partitionmanager 1.0.2 on squeeze

[Nick Boyce]

I've just tried creating a test partition on the only advanced format hard 
drive I have, which is a new Toshiba DT01ACA200 attached to a system still 
running squeeze (but with the 3.2.0 kernel from backports), with 
partitionmanager 1.0.2-1 (identical functionality presumably to the wheezy 
version).

Creating a partition leaving the "free space before" at its default value of 
0MiB results in a partition that begins at sector 63.  The HTML "operation 
report" produced at the end shows that ext4 filesystem creation produces the 
following warning:

  Command: mkfs.ext4 /dev/sdb1 
  mke2fs 1.41.12 (17-May-2010)
  /dev/sdb1 alignment is offset by 512 bytes.
  This may result in very poor performance, (re)-partitioning suggested.
  Filesystem label=
  OS type: Linux
  Block size=4096 (log=2)
  Fragment size=4096 (log=2)
  Stride=1 blocks, Stripe width=0 blocks

i.e. the partition is reported misaligned by 1 logical sector.

If I repeat the test but specify a "free space before" of 1MiB, then the new 
partition begins at sector 16065 (see below), and filesystem creation reports :

  Command: mkfs.ext4 /dev/sdb1 
  mke2fs 1.41.12 (17-May-2010)
  /dev/sdb1 alignment is offset by 3584 bytes.
  This may result in very poor performance, (re)-partitioning suggested.
  Filesystem label=
  OS type: Linux
  Block size=4096 (log=2)
  Fragment size=4096 (log=2)
  Stride=1 blocks, Stripe width=0 blocks

i.e. the partition is reported misaligned by 7 logical sectors.
The seemingly bizarre start sector 16065 would correspond in "virtual" (BIOS-
style) CHS disk geometry to 255heads x 63sectors, i.e. 1 cylinder, so it's 
possible that partitionmanager has a further bug where it works in cylinders 
even when claiming to work in MiB  :) 

It is not possible to use the "free space before" widget to enter a quantity 
in any unit other than MiB, so it appears impossible to create a properly 
aligned partition.

Cheers,
Nick