Red Hat Bugzilla – Bug 59141
Linux system with mylex card can not boot DOS anymore
Last modified: 2007-04-18 12:39:38 EDT
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Description of problem:
I am reporting this problem against the filesystem component having not found
a "fdisk" component to report against. Please redirect this bug if necessary.
I am installing RH Linux 7.2 on a server with a mylex card. (I have reproduced
the problem with an AcceleRAID 250 and an AcceleRAID 160 card)
The server has a maintenance partition, which is really a 10MB DOS-bootable FAT
partition which ID has been changed to 12 (hex). The purpose of this
maintenance partition is to provide hardware diagnostic tools and other
RedHat is then installed on the machine with a 4GB root ( / ) partition and a
300MB swap partition (located in the extended partition).
Once RedHat is installed, the server can not boot DOS in the maintenance
partition. Booting a DOS-bootable floppy proves impossible as well.
Within RedHat, if I delete the swap and extended partitions, I can then boot
from the maintenance partition (or from a DOS-bootable floppy), suggesting that
DOS was getting disturbed by something in the partition tables.
If I remove the mylex card from the server and use the onboard adaptec
controller to control the system disk, I have no problems. Same disk, same
partitionning scheme, no problem (I was also using the same disk in RAID 7 on
the mylex card).
The same configuration does not give any problem under RedHat 7.1 or 7.0. (but
the root filesystem is formatted with ext2 instead of ext3)
Finally, fdisk does behave so well when I play with the partitions. It keeps
complaining about the differences between physical and logical boundaries of
partitions. And (re)creating the extended and swap partitions proves to be a
If I use fdisk /dev/rd/c0d0
I can only create one big logical partition within the extended.
I have to use fdisk -u /dev/rd/c0d0 to be able to specify a size to a logical
I have used a 9GB and a 36GB disk and seen the same results. I use the mylex
cards with the 8GB-bios translation enabled.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Use a system configured with a mylex board.
2. Create a 10MB DOS partition.
3. Install RedHat with 4GB root, 300MB swap
4. try to reboot from a DOS-bootable floppy and see it hanging.
Actual Results: Booting from DOS hangs.
Expected Results: Booting from DOS should work.
fdisk is part of util-linux.
So actually, this is not how you would reproduce the problem.
To reproduce create a 10MB DOS formatted partition.
During install, chose disk druid to partition the disk and chose a 4GB root,
then once linux installed, log on and launch fdisk /dev/rd/c0d0 and create an
Reboot and see that DOS does not boot any longer.
After more investigation, it seems that the problem resides with the ability of
fdisk to get the correct disk geometry.
If I launch sfdisk, it will report to me that my disk has a C H S geometry of
4425/255/63. If I force these settings on fdisk (mode expert and then c h s), I
can then properly create an extended partition and fdisk does not complain
about differences between physical and logical boudaries anymore.
What geometry is fdisk incorrectly retrieving?
Also, it would be very helpful if you could test against the packages under
fdisk shows a geometry of 1 cylinder, 1 head and millions of sectors.
I will try these packages when I get the chance. Thanks.
Tested package util-linux-2.11n-6.i386.rpm dowloaded from
fdisk now sees the correct geometry.
Can close this problem report as far as I am concerned. (I let you close the
problem as I do not know what resolution I should select.)