Solution to Permission denied to /etc/mtab

I was setting up a hypervisor for RHEV running a full RHEL6 install instead of RHEV-H, and I wanted to tune it for better hypervisorness.

So I thought, Hey! I'll install tuned, since I am all excited about tuned after viewing the slides from Mark Wagner's Achieving Top Network Performance (PDF) at the 2012 Red Hat Summit. I was particularly excited about slide 12 entitled "Teaser 3 - latency."

Solution to VM missing from Virtual Machine Manager

I restarted a standalone KVM host running RHEL6 and when I opened Virtual Machine Manager, my guest virtual machine wasn't listed at all.

Eek!

Turns out I had been messing around with the XML definition in /etc/libvirt/qemu/machinename.xml (I know, I know...consider my hand slapped) and broke it. Fortunately /var/log/libvirt/libvirtd.log was kind enough to let me know what went wrong:

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Using RHEL6 to share RAID volume via iSCSI: the Mystery of the Missing LUN

My use case was pretty simple. I wanted to share out a raw device via iSCSI to a nearby host on the 172.16.2.x network.

In addition to a minimal Red Hat Enterprise Linux 6 (or equivalent) install, a few packages are needed:

# yum install -y iscsi-initiator-utils scsi-target-utils sg3_utils lsof

I knew the device I wanted to share was /dev/sdb by looking at the output from dmesg:

RHEV 3.0 Firewall Annotated iptables Configuration for Netfilter

When Red Hat Enterprise Virtualization Manager for Servers is installed, it offers to configure iptables for you:

...
Firewall ports need to be opened.
You can let the installer configure iptables automatically overriding the current configuration. The old configuration will be backed up.
Alternately you can configure the firewall later using an example iptables file found under /usr/share/rhevm/conf/iptables.example
...

Here's an annotated version of what the RHEVM installer will give you:

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