System Garbage Collection Method and Method for Garbage Collection in Solid State Disk

A system controller determines a to-be-collected first logical chunk group. The first logical chunk group includes a first data logical chunk located in a first solid state disk of the plurality of solid state disks. Valid data is stored in a first logical address in the first logical chunk group, and there is a correspondence between the first logical address and an actual address in which the valid data is stored. The system controller creates a second logical chunk group. At least one second data logical chunk in the second logical chunk group is distributed in the solid state disk in which the first data logical chunk storing a valid data is located in order to ensure that the valid data is migrated from the first logical chunk group to the second logical chunk group, but an actual address of the valid data remains unchanged.