[root@Cent6 /]# fdisk /dev/sdb Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel with disk identifier 0x039c48e3. Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable. Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) WARNING: DOS-compatible mode is deprecated.
It's strongly recommended to switch off the mode (command 'c') and ...
원문 링크 : [Linux] mdadm 설정 방법