Diagnosis and Performance Monitoring - Deploying and Managing a Cloud Infrastructure - page 152

Configuration tracking is an approach in which special software is employed to track
the various settings and configuration used in the system that happen across virtual and
physical environments. Understanding what sort of impact a certain change will bring is
quite difficult sometimes, but it starts with authorization. If a change was not authorized,
chances are it is an error or a breach may be occurring at that instance. But even though
certain changes have been assessed and mandated, understanding the potential impact of
those changes is still a constant challenge. It's this area of uncertainty where IT services
sometimes lose control, and this breeds an environment that is vulnerable to security
breaches, service infractions, or inability to comply as well as causing outages.
An organization must have a firm grasp of the configuration of its system and must
balance dynamic business needs and initiatives without losing control. The formula for
doing this is found in the section “Configuration Management” in Chapter 4, “Cloud
Management.”
Common Issues
In a system with hundreds of different components that range from physical hardware to
various firmware and software applications that are essential to the system functioning
properly, one of them is bound to eventually fail. Software is easy to fix through configura-
tion or reinstallation, but hardware must always be totally replaced when it fails. Here are
some common hardware failure issues.
Disk Failure Disk failure is one of the most common types of failure you will see in a data
center environment, especially one with vast storage area networks (SANs) used to keep
up with customer database demand. This one is common because the HDD is composed
of mechanical parts that are very small and moving at extremely high speeds. Because of
the size of the mechanical components, they cannot be made to be absolutely durable, so a
common failure point for any hard drive is its mechanical part. The electronic components
like the controllers can fail as well.
A disk that is about to fail will often have various obvious symptoms like bad sectors despite
proper file system management and maintenance and slower I/O speeds than expected, or
it will shut down and then restart. A drive could fail and then after reboot run again for a
while. This is a sure sign that the drive will totally fail in the near future. Constant backups
and employing RAID configurations can mitigate the resulting impact, but they can never
stop the inevitability of a disk failure.
HBA Failure Host bus adapters are pretty much like network interface controllers; they
are separate modules attached to the module slots of a computer system. The HBA serves
to provide I/O processing as well as physical connectivity between a server and a storage
device or cluster of devices. They serve to offload processing from the CPU so that it can
concentrate on other matters.