Dell PowerEdge R420 Technical Guide - Page 32

The static rails (shown in Figure 9) support a wider variety of racks than the sliding rails but do not support serviceability in the rack and are therefore are not compatible with the CMA. Figure 9. Static rails One key factor in selecting the proper rails is identifying the type of rack in which they will be installed. Both the sliding rails and the static rails support tool- less mounting in 19"- wide, EIA- 310- E compliant square hole and unthreaded round hole 4- post racks. Both also support tooled mounting in threaded hole 4- post racks, but only the static rails, as the more universal solution, support mounting in 2- post (Telco) racks. Table 19 lists the rack types that the R420 supports. The R420 is backward compatible with the R410 rails and CMA. Product Rail Identifier A7 R420 A8 Table 19. Supported rack types Mounting Interface ReadyRails II ReadyRails Rail Type Sliding Static Rack Types Supported 4-Post 2-Post Square Round Thread Flush Center    X X     Other key factors governing proper rail selection include the spacing between the front and rear mounting flanges of the rack, the type and location of any equipment mounted in the back of the rack such as power distribution units (PDUs), and the overall depth of the rack. Due to their reduced complexity and lack of need for CMA support, the static rails offer a greater adjustability range and a smaller overall mounting footprint than the sliding rails. For detailed information about static and sliding rails, see the Rack rail specifications section in Appendix A. For more information on installing the R420 in a rack, see the Rack Installation Instructions on Support.Dell.com/Manuals. 32 PowerEdge R420 Technical Guide