ASHRAE Journal - June 2019 - 53

TECHNICAL FEATURE

Compliance for IT Equipment
TABLE 1 CITE system-level thermal telemetry.
(CITE), for the ﬁrst time, estabSENSOR
SENSOR NAME
ACCURACY TIER 1 TIER 2 TIER 3
lishes an alignment on a comSystem Air Inlet Temperature
sys_temp_air_inlet
± 1°C (1.8°F)
Yes
Yes
Yes
mon set of power and cooling
System Air Inlet Temperature
sys_temp_air_inlet_min
N/A
Yes
Yes
Yes
telemetry and metrics within
Minimum Allowable
the IT industry for servers. CITE
System Air Inlet Temperature
sys_temp_air_inlet_max
N/A
Yes
Yes
Yes
categorizes the telemetry into
Maximum Allowable
three tiers:
Bulk Air Delta Temperature
blk_temp_air_delta
± 2°C (3.6°F)
No
Yes
Yes
* Tier 1 reﬂects the minimum or basic set of telemetry
Bulk Air Outlet Temperature
blk_temp_air_outlet
± 2°C (3.6°F)
No
Yes
Yes
required to allow for basic inteSystem Liquid Inlet Temperature
sys_temp_liq_inlet
± 2°C (3.6°F)
No
Yes
Yes
gration into DCIM systems;
sys_temp_liq_inlet_max
N/A
Yes
Yes
Yes
System Liquid Inlet Temperature
* Tier 2 reﬂects a more
Maximum Allowable
comprehensive set of telemetry
System Adjusted Liquid Inlet sys_temp_liq_inlet_max_adjusted
± 2°C (3.6°F)
No
No
Yes
based upon additional sensors
Temperature Maximum Allowable
that should be enabled in fuSystem Liquid Outlet Temperature
sys_temp_liq_outlet
± 2°C (3.6°F)
No
No
Yes
ture IT equipment designs; and
* Tier 3 reﬂects the most
comprehensive set of telemetry that could be utilized
those tiers that make the most sense for a given market
from IT equipment to unleash the full potential of future segment-since each sensor point can increase cost in
DCIM predictive solutions.
terms of hardware and the network bandwidth required
IT equipment telemetry generally falls into three
to transmit the data to the DCIM system through the
categories: system, chassis and component levels.
network.
Component-level telemetry (i.e. telemetry from comThe ASHRAE CITE provides guidance on thermal and
ponents such as processor (CPU), memory, disk) is pripower system, chassis and component telemetry. In
marily used as control input to server fan speed control
addition, CITE includes a category of other relevant sysalgorithms and is generally the least valuable to the
tem level telemetry that includes items like the system's
data center. System-level telemetry on the other hand,
ASHRAE environmental class (A1 - A4), airﬂow rate and
while also used in server fan speed control algorithms, is power supply efﬁciency.
more commonly intended to be exposed externally for
rack- or room-level integration to a DCIM system. Table 1 DCIM Compliance for Facility Operational Technology (OT)
Equipment
shows an example of the IT equipment system-level
OT is deﬁned as Operational Technology and is conthermal telemetry as part of CITE. Among the key feasidered to be the hardware and software dedicated to
ture of CITE are a consistent sensor naming convention
detecting or controlling the facility's power and cooling
and an industry-recognized deﬁnition for each sensor.
infrastructure and ensuring data center uptime and
These attributes are important to avoid further confuresiliency. As with the IT equipment, the operational
sion regarding what is being measured across different
technology (OT) telemetry provides a lot of value to
IT manufacturers.
The CITE tiers give data centers the opportunity to take the DCIM system. While writing Advancing DCIM with
advantage of IT equipment telemetry in their DCIM sys- IT Equipment Integration it became apparent that while
tem with CITE Tier 1 IT equipment. In fact, many servers not as proprietary as the IT equipment nomenclature
today already expose these Tier 1 sensors to the data cen- and protocols, access to OT equipment telemetry also
beneﬁted from categorization into three levels. These
ter - albeit with proprietary nomenclature and APIs. As
levels focus on the telemetry aspects of power and
IT manufactures adopt CITE, the deployment of DCIM
cooling hardware. The term level is used to keep its
tools that can leverage IT Equipment should become
structure separate and independent from that of the IT
easier. Furthermore, by dividing CITE into three tiers,
tiers. The reason for this is to create a distinction and
IT manufacturers have the advantage of supporting
J U N E 2 0 19

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