1. 按照block为1M单位分割
dd if=dgjd of=zz1 bs=1M count=20000000 skip=0
dd if=dgjd of=zz2 bs=1M count=20000000 skip=20000000
dd if=dgjd of=zz3 bs=1M count=20000000 skip=40000000
dd if=dgjd of=zz4 bs=1M count=20000000 skip=60000000
dd if=dgjd of=zz5 bs=1M count=20000000 skip=80000000
2.恢复文件
cat zz1 zz2 zz3 > filename