POWER MANAGEMENT
Firm favors switched PDUs
High rate of failure led real estate
company to new solution for its data
centers.
Increasing power densities, combined with
enhanced product functionality, have created
strong demand for cabinet power-distribution
units (PDUs) within today’s data centers.
The type and amount of power delivered to
the cabinet can greatly affect costs,
cooling efficiency, redundancy and future
expansion plans within these facilities. At
Colliers Turley Martin Tucker (CTMT), a
full-service commercial real estate firm,
implementing switched PDUs was necessary in
order to service and support its data center
customers.
The capability to install and
monitor two individual probes per PDU
ensures that these measurements can be
made exactly where they are required.
CTMT handles more than $4 billion in
annual real estate transactions and manages
in excess of 140 million square feet of
office, industrial and retail space. CTMT
has more than 1,100 associates throughout
its regional offices in Cincinnati, Columbus
and Dayton, Ohio; Indianapolis; St. Louis
and Kansas City, Mo.; Minneapolis/St. Paul;
and Nashville, Tenn.
When CTMT took over the management of
data centers in St. Louis and Tempe, Ariz.,
however, they were already populated with
racks and PDUs. Since CTMT wanted to keep
things uniform, the same PDUs were also used
for all new installations.
Generally, the CTMT staff thoroughly
tests each PDU prior to installation. Each
site is equipped with a custom-built test
station, and has written and approved
testing and configuration procedures for
each type of PDU in use. This practice,
however, was not in place during the initial
build-out of these data centers.
“We have always used cabinet PDUs, but
previously used other brands, which caused
reliability issues,” says Chris Wanger, CTMT
data center manager.
CTMT began to notice a high rate of
failure in the PDUs they were receiving,
Wanger says. Additionally, after only a
couple years of service in the data center
environment, PDUs began failing in the
cabinets, with numerous and varied types of
failures. “It was clear that changes had to
be made,” he adds.
Legacy problems remain
“We are still dealing with problems
related to the other manufacturer’sPDUs,”
explains Wanger. “For instance, on an
eight-outlet PDU,we have to schedule
downtimewith sometimes several different
equipment owners to enable us to change the
PDU. Some PDUs have outlets that powered
themselves off and will not allow them to be
turned back on.”
CTMT’s critical-facilities team, directed
by John Scheer, who manages data centers in
St. Louis, Tempe, Ariz., Orlando, Fla.,
Cincinnati, Toronto and the United Kingdom,
says critical factors when specifying IT
equipment for data centers include
reliability and functionality, with strong
customer support and service. This belief
led CTMT to search out vendors capable of
delivering high-quality products that
provide unique technical advantages and
solutions.
The CTMT staff researched new
alternatives from numerous PDU
manufacturers, with a number of evaluation
units tested. Server Technology (STI)
offered all the options that CTMT thought it
would need in a PDU, Wanger says, including
a customizable product.
During installation, a laptop computer is
used, along with the native Hyperterm
application, to access the Server Technology
integral user interface. “The ServerTech PDU
software provides more than enough critical
information to the user, all through the
simplistic Hyperterm application,” explains
Wanger.
A secure Web-based, IP-enabled interface
is available, allowing both in-band and
out-of-band communications with the PDU. The
IP-based communication protocols include
HTTP, HTTPS, Telnet and SSH. Other
communication tools include LDAP, LDAPS,
TACACS+, DHCP and a serial interface.
“Our St. Louis andTempe siteshave250 to
300standard racks each,” Wanger says. “Both
sites have a 30-inch raised floor, 36,000
square feet each, and both sitesare capable
of providing either 120 or 208 VAC,static or
non-static power. In all cases, we try to
primarily use 208 VAC, unless certain
equipment requires 120. On allmulticorded
equipment, each power supplycan be traced
all the way back to different UPS units,
providing complete redundancy. We monitor
and record power all the way to the
individual equipment cords.”
A couple of years ago, CTMT began using
STI’s Sentry switched cabinet distribution
units (CDU), which come in both single- and
dual-fed power configurations, in order to
solve the problem of employees completely
bypassing the facilities team by installing
and plugging in equipment. Often, this meant
the equipment was plugged in incorrectly,
creating extra work, because once they are
discovered, an outage is required to make
corrections. With switched STI PDUs, unused
outlets are turned off so the facilities
personnel must be present during all new
installations, allowing direct supervision
of the installation, including which power
sources and outlets are utilized for any new
equipment.
Lead time reduced
When customers decide to install new
hardware, and their requests must be
supported in a timely fashion. With CTMT’s
previous PDU supplier, the average lead time
was five weeks, and in several instances,
orders were delayed six to seven months.
Since switching to STI PDUs, Wanger says,
CTMT has not had a lead time greater than
seven days.
STI PDUs can be ordered with
temperature/humidity probes that have
generous lead lengths, Wanger says. This
feature is essential for those racks in
which heat density is an issue and requires
monitoring.
The capability to install and monitor two
individual probes per PDU ensures that these
measurements can be made exactly where they
are required, providing the highest level of
accuracy. Alarm and output information is
available via an integral interface, SNMP
traps or e-mail alerts.
“The LEDs provide a useful indication of
which outlets are powered on,” Wanger says.
“And the user interface, when used with a
laptop or IP-based monitoring software,
provides detailed, useful information. We
often connecta laptop to each PDU in order
to retrieve up-to-date power readings.”
Other benefits include power monitoring
via Internet protocol (IP) and environmental
(temperature and humidity) monitoring via
IP. “We have just begun to use the optional
temperature and humidity probeson some of
our warmer racks, but
with our older PDUs, we do not even
have that option,” Wanger says.
For more information from Server
Technology, Reno, Nev.:
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