Install grub with multiple partition labels error

今天在试图将root文件系统迁移到一块空白磁盘时，遇到了一个安装grub的错误:

    root@bcat:~# grub-install /dev/sdc
    Installing for i386-pc platform.
    grub-install: warning: Attempting to install GRUB to a disk with multiple partition labels.  This is not supported yet..
    grub-install: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists

are UNRELIABLE and their use is discouraged..
grub-install: error: will not proceed with blocklists.

非常奇怪的一个问题，在网上乱找，发现这个帖子，猛然想起这个磁盘曾经被不小心写
入过ISO文件。于是按照帖子的内容执行了dd

    dd if=/dev/zero of=/dev/sdc seek=1 count=2047 bs=1b

这个命令会在磁盘的开始写入1M的zero，由于Linux下使用fdisk进行分区时会空出前2048个块，
所以执行这个命令不会影响现有的数据，执行完毕后，grub可以顺利安装

    root@bcat:~# grub-install /dev/sdc
    Installing for i386-pc platform.
    Installation finished. No error reported.
    root@bcat:~#