DualBoot Centos7-Windows7

$> fdisk -l

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes, 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: dos
Identificador del disco: 0xd3d542f1

Disposit. Inicio    Comienzo      Fin      Bloques  Id  Sistema
/dev/sda1   *        2048   417519615   208758784    7  HPFS/NTFS/exFAT
/dev/sda2       417519616  1543919615   563200000    7  HPFS/NTFS/exFAT
/dev/sda3      1543919616  1544534015      307200   83  Linux
/dev/sda4      1544534016  1953523711   204494848    5  Extended
/dev/sda5      1544538112  1949329407   202395648   83  Linux
/dev/sda6      1949331456  1953523711     2096128   82  Linux swap / Solaris

Disk /dev/sdb: 15.5 GB, 15479597056 bytes, 30233588 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Identificador del disco: 0x001fdc1c

Disposit. Inicio    Comienzo      Fin      Bloques  Id  Sistema
/dev/sdb1   *        2048    30233587    15115770    c  W95 FAT32 (LBA)

$> blkid
/dev/sda1: UUID="20B2508FB2506AF4" TYPE="ntfs" 
/dev/sda2: UUID="B2B2EE91B2EE597D" TYPE="ntfs" 
/dev/sda3: UUID="eb96ed5f-66db-4c93-b4be-eb2b657166d1" TYPE="ext4" 
/dev/sda5: UUID="e8ba792c-c040-4f86-9f0e-2f537ceb1022" TYPE="ext4" 
/dev/sda6: UUID="dd20762b-5710-4c9f-bd62-0c722036c644" TYPE="swap" 
/dev/sdb1: LABEL="CENTOS 7 X8" UUID="30DA-6DC3" TYPE="vfat" 

$> cd /etc/grub.d/

Editar archivo
$> vim 41_custom 
------------------------------------------------------------
#!/bin/sh
cat <<EOF
if [ -f  \${config_directory}/custom.cfg ]; then
  source \${config_directory}/custom.cfg
elif [ -z "\${config_directory}" -a -f  \$prefix/custom.cfg ]; then
  source \$prefix/custom.cfg;
fi
EOF

cat <<EOF
menuentry "Windows 7" {
        insmod part_msdos
        insmod ntfs
        set root='hd0,msdos1'
        search --no-floppy --fs-uuid 20B2508FB2506AF4
        chainloader +1
}
EOF

-----------------------------------------------------------------------------------

$> grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-862.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-862.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-aa4fe872c9bd430e98c8e4e0bd9fa4ba
Found initrd image: /boot/initramfs-0-rescue-aa4fe872c9bd430e98c8e4e0bd9fa4ba.img
done
$> reboot