Business Continuity
Energy savings MAID to order
Intelligent power management can ensure performance and reduce electricity use.
by Bob Woolery
A new breed of MAID technologies takes advantage of idle time to save energy without sacrificing performance.
Ninety percent of all
stored data was untouched during a
three-month time frame, according to a
recent information access study conducted by
researchers at UC-Santa Cruz. This study
revealed a common but not well-understood
problem in data center management: Most data
centers run needlessly at full power around
the clock because of an incorrect assumption
regarding data usage.
A key first step in
reducing IT energy consumption is making
storage administrators aware that their
systems are running at full capacity much
more often than necessary. Far too many data
center managers are wasting large amounts of
money because they think their storage
systems need to run at full power 24/7.
In a typical data center,
most data requests come between 9 a.m. and 5
p.m. on weekdays. Those 40 hours only
account for 24 percent of a week, leaving
the potential for energy-efficient
approaches to data storage, especially on
nights and weekends.
Even businesses with 24/7
operations (such as hospitals) experience
significant data center idle time. The
central issue is how frequently data is
accessed and how quickly the servers can
respond–not how often the facility is open.
Many IT managers are
surprised to find out just how often their
information goes untapped. Data center
managers should know their organization’s
usage patterns to discern how easily savings
can be found. Data may need to be kept on
hand for long periods of time, but it does
not need to consume lots of energy all the
time.
Disk drives account for
about 80 percent of the energy used in data
storage systems. Therefore, addressing that
energy consumption is the most important
part of the solution.
For many years, massive
array of idle disks (MAID) technology has
been capitalizing on disk drive idle time to
save significant amounts of energy and, in
turn, money. Many users have criticized
MAID, however, because it has traditionally
put inactive disks to sleep and sacrificed
fast response times.
In response, a new breed
of MAID technologies (Greg Schulz, a market
analyst at The Storage IO Group, groups them
together as "MAID 2.0.") takes advantage of
idle time to save energy without sacrificing
performance. Herein lies the real
breakthrough in green data storage.
According to Schulz,
"MAID-enabled devices are evolving from
first-generation MAID 1.0 where hard disk
drives (HDDs) are either on or off, with
associated performance penalties, to
second-generation MAID, or MAID 2.0,
implementing intelligent power management
(IPM). With IPM-enabled MAID 2.0, instead of
HDDs being on or off, there can be multiple
power-saving modes to balance energy savings
with performance and availability needs."
By multiple power-saving
modes, Schulz refers to user-defined
settings such as these examples:
Level 1. After 15 minutes
of inactivity, the read/write heads will
automatically be unloaded. This simple step,
transparent to the user, enables energy
savings of approximately 20 percent. It
maintains a sub-second response time without
a power spike for the first I/O request. All
subsequent I/O requests are handled
instantaneously.
This setting signifies
the fastest response time, while still
enabling energy savings. For busy
organizations such as hospitals, this
feature provides fast access to patient
records but can achieve energy savings when
there are idle periods.
Level 2. After 30 minutes
of inactivity, the speed of the drive
platters will automatically be reduced to
4,000 RPMs. The first I/O request will be
handled within 15 seconds and all subsequent
requests will be handled instantaneously.
This level achieves at least 40 percent
energy savings and is generally used for
data that is occasionally, but not
frequently, accessed, such as archived word
processor files, spreadsheets and
presentations.
Level 3. After 60 minutes
of inactivity, the disk drive is placed into
a light sleep, yet is still able to respond
to an initial I/O request within 30 seconds.
As in Levels 1 and 2, subsequent requests
will be handled instantaneously. Level 3
enables energy savings of 60 percent or more
and is ideal for the long-term archiving of
fixed-content data, such as e-mails,
financial records and medical tests.
Government regulations mandate that many of
these files be kept anywhere from decades to
an infinite length of time, so organizations
need to keep them on hand even if they are
not regularly accessed.
In addition to enabling
substantial reductions in energy costs, MAID
2.0 technologies are also easy to use. They
adhere to the "set it and forget it"
philosophy. After a few simple mouse clicks
by an administrator, the energy savings take
place automatically and dynamically without
any additional human intervention.
With cost reduction now a
major focus, data center managers can be
expected to look at how frequently their
data is idle. They will find that it goes
untouched much more often than they think.
They will also discover that MAID 2.0
technologies can help cut energy costs by 20
percent to 60 percent or more, without
impacting performance.
Bob Woolery is senior vice president of marketing for
Nexsan Corp., Thousand Oaks, Calif.
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