Offering 94%+ efficienct redundant power supply support, 847 Series features 36 hot-swap 3.5 in. hard drive trays with 24 in front and 12 in rear. For JBOD configurations, chassis can support 21 HDDs in rear for total of 45 hot-swap 3.5 in. HDDs. All models support both uni-processor and dual-processor serverboards and feature hard drive signal trace routing. With 100% cooling redundancy, systems will continue operating without performance loss if internal cooling fan fails.