Fdisk disagreas with BIOS over 120GB drive.

Siegbert Baude Siegbert.Baude at gmx.de
Tue Aug 19 09:14:19 PDT 2003


>>Fdisk (using /stand/sysinstall) disagrees with the values my bios is 
>>reporting.  My BIOS reports that my 120GB drive has this geometry: 59131 
>>Cylendars, 16 Heads, and 255 sectors.  The drive is an IBM deskstar.  When i 
>>try to enter the correct geometry, Fdisk gives me the message below. 
>>---------start message--------- 
>> 			        Message 
>>     WARNING:  A geometry of 59131/16/255 for ad2 is incorrect.  Using 
>>     a more likely geometry.  If this geometry is incorrect or you 
>>     are unsure as to whether or not it's correct, please consult 
>>     the Hardware Guide in the Documentation submenu or use the 
>>     (G)eometry command to change it now. 
>>     Remember: you need to enter whatever your BIOS thinks the 
>>     geometry is!  For IDE, it's what you were told in the BIOS 
>>     setup. For SCSI, it's the translation mode your controller is 
>>     using.  Do NOT use a ``physical geometry''. 
>>     (100%) 
>>                                [  OK  ] 
>>      			   Press enter or space 
>>----------end message---------- 
Sorry, i just had a closer look at the CHS numbers 59131/16/255 fdisk 
spits out and it is completely correct, this is no valid geometry!
For all the glory details read:


In short, the number of sectors should be <=63. I remember, that I had 
the same problem with an Samsung SV1204H (also 120GB) and an Abit-BX133. 
I had to manually insert the correct numbers there. The disk reports 
232632/16/63, but due to a small bug in the BIOS, I couldn't choose a 
cylinder value of 232632. So I used the 14596/255/63 mode. Note, that 
the sector number in both cases is <=63. The number of cylinders can 
slightly vary for your IBM disk.

So I suggest to erase the partition table as I described before and then 
force the BIOS to use either the 16/63 (if possible) or 255/63 mode.


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