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Can I Use Multiple Virtualization Technologies Simultaneously under Linux?

Q. I was reading this article and wanted to try out KVM, XEN, VMWare and VirtualBox simultaneously on my desktop system with 2GB RAM? Why I'm not able to use run multiple virtualization technologies simultaneously under Ubuntu Linux? Can a powerful Linux server run multiple virtualization technologies simultaneously?
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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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Linux bnx2: eth1: No interrupt was generated using MSI, switching to INTx mode

Q. I see following message in my logs files:

Linux bnx2: eth1: No interrupt was generated using MSI, switching to INTx mode

My server hangs occasionally after rebooting with above message in /var/log/message. How do I get rid of this problem under CentOS Linux / RHEL version 4.x?
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Install VMware Tools In Ubuntu Linux ( VMwareTools-1.0.5-8017.tar.gz file )

Q. How do I install VMware tools (virtual server tools) in Ubuntu Linux to improve the performance of the guest VPS (VM machine) system?
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FreeBSD make: don't know how to make buildkernel. Stop Error and Solution

Q. I'm trying to recompile my kernel by tying the following commands:

cd /usr/src/sys/i386/conf
cp GENERIC NEWKEN
vi NEWKEN
cd /usr/src
make buildkernel KERNCONF=NEWKEN

But I'm bumped with an error that read as follows:

make: don't know how to make buildkernel. Stop Error and Solution

How do I fix this error?
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Force yum update Command To Exclude Certain Packages

How can I exclude selected packages when I rum yum update command under CentOS / RHEL / Fedora / Red Hat Enterprise Linux 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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How To Upgrade FreeBSD 6.3 to 7.0 Stable Release

Q. FreeBSD 7.0-RELEASE is now available for the 64 and 32 bit computer architectures. How do I upgrade FreeBSD version 6.3-pX 64 bit to latest 7.0 64 bit system?
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FreeBSD Install Strace – A Process Tracer And Debugging Tool

Q. How do I install Strace utility under FreeBSD operating system so that I can trace and debug my applications and report 3rd party software bugs?

A. Strace is a process tracer, i.e. a debugging tool that prints out a trace of all the system calls made and signals received by a process itself or a process and its descendants.

Strace is similar to the native BSD truss utility, but it's output style is more convenient in most cases.

For strace to work, procfs has to be mounted. FreeBSD does not mount it by default.

WARNING! These examples only work for i386 32 bit FreeBSD computer (strace is not ported to amd64 arch [64 bit]).

Install strace

First update FreeBSD ports collection and install strace from /usr/ports/devel/strace:
# portsnap fetch update
# cd /usr/ports/devel/strace
# make install clean

Mount /proc file system

You need to mount /proc filesystem to use trace command under FreeBSD, enter:
# mount -t procfs proc /proc

How do I use Strace tool?

Please see our previous FAQ / tutorials about strace command:

  1. Debugging Tip: Trace the Process and See What It is Doing with strace
  2. Truss like command under Linux to monitor and diagnostic the system calls

Linux kernel: Uhhuh. NMI received for unknown reason 30

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