Snapshot method and device of storage system, electronic equipment and readable storage medium

The invention discloses a snapshot method and device of a storage system, electronic equipment and a readable storage medium. The method comprises the steps that when it is detected that a copy-on-write snapshot is created, a corresponding bitmap is automatically allocated to a source volume; the bits of the bitmap are in one-to-one correspondence with the data blocks of the source volume; when a data write-in request is received, whether copy-on-write needs to be carried out or not is judged according to the flag bit of the bitmap and the data backup failure record information; if copy-on-write needs to be carried out, firstly data in the source volume is copied to the snapshot volume, the bitmap is updated, and then to-be-written data corresponding to the data writing request is written into the source volume; and if the copy-on-write does not need to be carried out, the data to be written is directly written into the source volume. According to the method and the device, data backup can be realized in a co