ODIN conducted two tests, which included placing tags directly onto six sticks of
RAM, as well as affixing tags to the heat sink covers over two sticks of RAM. In each scenario, a handheld
interrogator was used to determine the total number of redundant reads at close range over a period of five seconds, with the
reader oriented both parallel and perpendicular to the RAM sticks. Each test was repeated with the server case cover in place, with only the plastic RAM covering on, and with the RAM sticks completely exposed.
During the five-second test, ODIN documented the number of redundant reads. If a high number were documented, the test would prove that
tag able to work consistently. If there were only a few redundant reads, however, chances are the tag would not be a consistent—and, thus, viable—option.
Of the two tags, one consistently outperformed the other (ODIN has asked that
RFID Journal not identify individual tags' performance, though that data is available in the report). The poor-performing tag was unable to function when placed upon RAM without a heat sink, because it needs to be attached to a metallic object to consistently provide reads. In contrast, the other was able to perform adequately on bare RAM since it need not be attached to a metallic object to function properly.
According to Bennett, the test showed that sweeping the handheld over the RAM perpendicularly was more effective than passing it over in a parallel manner, and reads were better when the plastic cover was closed over the RAM. As expected, he adds, no reads were possible when the server's metal case was closed.
"A lot of this gets down to, in this case, where the tags are positioned [and sending RF signals], in the gaps between the [sticks] of RAM," Bennett says. "That will certainly cause interesting reflections." When tags give off signals, he adds, those waves often reflect off of nearby objects, particularly with metal. The RF signals can also be absorbed by plastic and silicon. "It is quite possible because of that, at least in this use case, you
saw the results we had."
Nonetheless, Bennett says, the test demonstrates that
RFID is effective for inventorying RAM sticks if the proper tags are selected, and if the correct methods are employed to interrogate those tags. "Reading tags attached to RAM is not always a straightforward process," he states, "and it very much depends on the tag you are using, whether a cover is on and the type of RAM—but it is possible."
The IT
Asset Tracking Benchmark is now available for downloading from
ODIN's Web site. The cost is $1,500 for an enterprise-wide business license; educational institutions can contact ODIN for a free copy of the report.