Techniques provide for data rebuilding in a storage system. The techniques involve: in response to failure of a first disk in the storage system, determining a second disk having a high risk of failure in the storage system; determining whether the second disk contains a second data block that is associated with a first data block to be rebuilt in the first disk, the first and second data blocks being from a same data stripe in the storage system; and in response to determining that the second disk contains the second data block and the second data block has not yet been replicated into a third disk for backup in the storage system, reading the second data block from the second disk to rebuild the first data block, and replicating the read second data block into the third disk.