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grub.conf

HowTo: Turn off SELinux

How do I turn off SELinux (Security-Enhanced Linux) under Linux operating systems?
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In our research lab I'd like to disable all USB devices connected to our HP Red Hat Linux based workstations. I'd like to disable USB flash or hard drives, which users can use with physical access to a system to quickly copy sensitive data from it. How do I disable USB device support under RHEL 5.x workstation operating systems?
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Linux: Skip or Bypass a Fsck

Q. I know how to force fsck on the next reboot using /forcefsck file. But how do I skip or bypass a fsck on reboot? How to stop a FSCK from prompting or running automatically when rebooting server.
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Q. My CDROM drive attached to Stratus ftServer 6210 is not working and it is dumping me with following error:

hdb: lost interrupt
hdb: lost interrupt

hdb: lost interrupt
hdb: status error: status=0x59 { DriverReady SeekComplete DataRequest
Error }
hdb: status error: status=0x40 { LastFailedSense=0x04 }
ide: failed opcode was: unknown
hdb: drive not ready for command
hdb: lost interrupt
hdb: status error: status=0x59 { DriverReady SeekComplete DataRequest
Error }
hdb: status error: status=0x40 { LastFailedSense=0x04 }

How do I fix this error under Linux?
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Q. I've upgrade my CentOS / RHEL (Red Hat Enterprise Linux) 4.7 on HP ProLiant DL580 G5 and it is showing unknown NMI errors in the logs:

Uhhuh. NMI received for unknown reason 30.
Dazed and confused, but trying to continue
Do you have a strange power saving mode enabled?

Uhhuh. NMI received for unknown reason 20.
Dazed and confused, but trying to continue
Do you have a strange power saving mode enabled?

How do I fix this error?
A. This is caused when the system is hanging under load. Add any one of the following to you /boot/grub.conf file:

  1. Disable the NMI watchdog by adding "nmi_watchdog=0"
  2. Disable the high precision event timer (HPET) by adding "nohpet"

Open grub.conf, type:
vi grub.conf
Make modification to kernel line as follows:

title Red Hat Enterprise Linux AS (2.6.9-78.0.8.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-78.0.8.EL ro nohpet root=/dev/VolGroup00/LogVol00 nohpet
        initrd /initrd-2.6.9-78.0.8.EL.img

Save and close the file. Reboot the server:
# reboot