Important Disclaimer: Those results as of yet are unconfirmed. Make backups and read carefully before you proceed.

--- You are operating at your own disk !! ---


Hi you probably came here from a search engine, on your desperate search to

>> solve, better avoid this infamous "partition table on device hda was unreadable" error message <<

, which pop up in many forums but nobody could actually provide a working solution.

Well, you can be helped... follow me and read on, I will try to pinpoint the issues real troublepoints.


Discussion:

- we are assuming that all Linux use the same harddisc geometry (512 byte /sector)
- This implements that we are not tuning this geometry somehow f.e. to 514...516 or 518 byte/sector)
- in other words we use fdisk, mkfs etc. as we should


1a) Make a plan for your partitions (mind the historical limitations)
- put boot partitions under the 1024 block limit (mainly for Lilo)
- mind the harddisc size limit by Bios (CHS,Large,LBA mode) - 500MB,2GB,137GB etc.


Notebook: IBM X31
HHD type: ... to be written ..
HDD advertised size: 40GB
heads: 240
sectors: 63
Cylinders: 5168 (Group A) Novell, Suse, Knoppix) (40007761920 bytes = 38.154GB (40GB shown))
Cylinders: 4685 (Group B) Red Hat, Mandrake, Debian) (36269228544 bytes =ca. 34.589 GB) (36,2GB shown)

Note :

>> Difference in reported cylinders for Group A) or Group B) when using the programme "fdisk" <<


- Mandrake will show only 33GB in the setup Wizard ( also different from Group B)
- Debian will point out the difference in /var/log/messages
...
current capacity is 70838337 sectors (36269 MB)- 4685 cylinders
native capacity is 78140160 sectors (40007 MB)- 5168 cylinders
...
CHS=65535/16/63


- Debian is also using a different hard disc geometry (scary ;-(


1b) CONFIRM which CHS settings your OS's fdisk sees

- Red Hat: At the "Welcome screen" (still at a command prompt) type "linux rescue" and "fdisk /dev/hda" and watch for the CHS parameters (write them down !!

- Debian: Start the rescue mode. Type "linux rescue" and "fdisk /dev/hda" and watch for the CHS parameters (write them down !!

O.K know that we know the HDD geometry lets continue to build our partitions.


1c) Consider the following partition layout on a 40GB advertised harddisc of a IBM X-31
(made with Knoppix):

Note: Knoppix will see all 5185 cylinders, but for now we have to play nice to let Red Hat and Debian accept the partition layout, which we will adjuyst later for the last partition and the extended partition:


/dev/hda1 1 1985 15006568+ 86 NTFS Volume
/dev/hda4 1986 4685 24063480 5 Extended
/dev/hda5 1986 1996 83128+ 83 Linux
/dev/hda6 1997 2007 83128+ 83 Linux
/dev/hda7 2008 2018 83128+ 83 Linux
/dev/hda8 2019 2029 83128+ 83 Linux
/dev/hda9 2030 2096 506488+ 82 Linux Swap
/dev/hda10 2097 2758 5004688+ 83 Linux
/dev/hda11 2759 3420 5004688+ 83 Linux
/dev/hda12 3421 4082 5004688+ 83 Linux
/dev/hda13 4083 4685 8210128+ 83 Linux

(The above data is in blocks)


These are the OS's which I installed

1) Windows (hda1)
2) Debian Sarge 3.1 - testing (fdisk v2.12p) (hda8,hda13)
3) Mandrake 10.1 - official (fdisk v2.12a) (hda6,hda11)
4) Red Hat EL 3.0 - ES (fdisk v2.11y) (hda7,hda12)
5) Suse Linux 9.2 - professional (fdisk v2.12c) (hda5,hda10)
6) Knoppix Edu 4 - ja (fdisk v2.12) (not installed)


Notes:

- hda1 contains some infamous OS from Redmond (www.somethingsoft.com/fakethefacts
- hda5-8 are the OS's boot partitions (ext3 format).
- hda9 is the swap partition
- hda10-13 are the actual OS's partitions (hda10,11,13 in reiserfs -
(Red Hat (Fedora 4) still doesnt support XFS,JFS and Reiserfs ;-(


Remaining open questions:

- O.K, now I got the point that Red Hat and Debian seems to use another hard disc geometry.

- Does that mean RedHat and Debian use a incompatible partition table format or that they just dont use all available disc space ?


--- The end ---



--- >> From here operate at your own risk !! << ---
-----------------------------------------------


See the above line ? Alright, thats it. You have crossed the border, right here.

- So you want to know how to proceed if you created partitions in Red Hat or Debian but want to use all harddisc space as claimed by Mandrake, Suse or Novell ?


--- >> From here operate at your own risk !! << ---



2) Install the first OS of your choice (f.e. Debian, Red Hat)

- Here Suse, Novell and Mandrakes fdisk seems to be advanced (seeing 5168 cylinders).
Lets start inserting Red Hat and Debian. Use Mandrake Suse or Novells Linux towards the end of the hard disc (will be installed and formatted later).


3) Recreate the partition layout within Suse, Novell's or Mandrakes fdisk. Pay attention to the details. Only the extended partition and the last partitions details change here:

Before (made with Knoppix):

/dev/hda1 1 1985 15006568+ 86 NTFS Volume
/dev/hda4 1986 4685 24063480 5 Extended
/dev/hda5 1986 1996 83128+ 83 Linux
/dev/hda6 1997 2007 83128+ 83 Linux
/dev/hda7 2008 2018 83128+ 83 Linux
/dev/hda8 2019 2029 83128+ 83 Linux
/dev/hda9 2030 2096 506488+ 82 Linux Swap
/dev/hda10 2097 2758 5004688+ 83 Linux
/dev/hda11 2759 3420 5004688+ 83 Linux
/dev/hda12 3421 4082 5004688+ 83 Linux
/dev/hda13 4083 4685 8210128+ 83 Linux


After (made with Knoppix):

/dev/hda1 1 1985 15006568+ 86 NTFS Volume
/dev/hda4 1986 5168 24063480 5 Extended
/dev/hda5 1986 1996 83128+ 83 Linux
/dev/hda6 1997 2007 83128+ 83 Linux
/dev/hda7 2008 2018 83128+ 83 Linux
/dev/hda8 2019 2029 83128+ 83 Linux
/dev/hda9 2030 2096 506488+ 82 Linux Swap
/dev/hda10 2097 2758 5004688+ 83 Linux
/dev/hda11 2759 3420 5004688+ 83 Linux
/dev/hda12 3421 4082 5004688+ 83 Linux
/dev/hda13 4083 5168 8210128+ 83 Linux

Notes:

- What is interesting is that Knoppix will see 5168 cylinders even though it is Debian based.


4) Install the remaining Linux up to the last partition (hda13)


More info on the same or similar issues:

http://lwn.net/Articles/86835/
http://www.linuxquestions.org/questions/showthread.php?postid=1061795