Hard disk backboard cascade expansion structure

The utility model belongs to the technical field of hard disk equipment, and particularly relates to a hard disk backplane cascade expansion structure, which comprises an SAS Expander main backplane and two straight-through auxiliary backplanes, an uplink port of the main backplane is led out by two Mini SAS connectors, 0-23 paths of a downlink port are connected with a hard disk through a hard disk connector, and the main backplane and the two straight-through auxiliary backplanes are connected with each other. And the 24-39 paths of the downlink port are connected with the two auxiliary backboards through four Mini SAS (Serial Attached SCSI) connectors. Therefore, one server can manage 40 hard disks only through one RAID card through the hard disk backboard cascade expansion structure, a large number of hard disk backboards can be expanded, flexible configuration can be carried out in combination with the limitation of the structure space, PCIE interface resources and the use number of RAID cards are effect