But for network cabinets, we use “U” instead. 45 millimeters, if you prefer metric). This standard was created by the Electronic Industries Alliance, or EIA. Because everyone uses the same measurement, all equipment works together smoothly. Important: U describes height only, but a server's real "capabilities" are also determined by chassis depth, internal layout, airflow, rails, power, and expansion (PCIe/risers, NVMe. The U space of cabinets is an important concept for people working on IT infrastructure, data centers, or managing networks. Whether you are an expert or just a beginner in the field, it can still be challenging to figure out the U sizes—from small 6U cabinets up to giant 48U ones—without proper. A rack unit, abbreviated as U (or RU), is a standardized unit of measurement used to describe the vertical space occupied by equipment in a server rack. This article explains definition, planning, installation tips, and trends.
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