이미지가 64MB이면 grub-install이 실패하고, 이미지가 256MB이면 grub-install이 성공합니다.

두 경우 모두 tst.sh 스크립트는 dd가 첫 번째 경우에 64MB 이미지를 생성하고 두 번째 경우에 256MB 이미지를 생성한다는 점을 제외하면 완전히 동일합니다. (이미지 크기는 스크립트의 첫 번째 dd 줄에 있는 count 매개변수로 정의됩니다.)

이미지 크기가 256MB이면 grub 설치가 오류 없이 실패하고, 이미지 크기가 64MB이면 grub 설치가 실패합니다.

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1. 버전:

(venv3.4)root@ugbuildserver:/home/ubuntu/ubuntucore# grub-install -V
grub-install (GRUB) 2.02~beta2-22ubuntu1.1

시나리오 1: dd count=64일 때 GRUB가 실패함

(venv3.4)root@server:/home/ubuntu/ubuntucore# cat tst.sh
sudo dd if=/dev/zero of=./test.img oflag=direct bs=1M count=64
sudo mkdir -p /mnt/build
sudo parted -s test.img mklabel msdos
sudo parted -s -a optimal test.img mkpart primary ext2 '0%' '100%'
sudo parted -s test.img set 1 boot on
sudo kpartx -av test.img
sudo mke2fs -L '/' -t ext2 /dev/mapper/loop0p1
sudo mount /dev/mapper/loop0p1 /mnt/build
sudo grub-install --root-directory=/mnt/build /dev/loop0

# release mount
sudo umount -l /mnt/build
# release loopback
sudo dmsetup remove loop0p1
sudo losetup -d /dev/loop0

(venv3.4)root@server:/home/ubuntu/ubuntucore# . tst.sh
64+0 records in
64+0 records out
67108864 bytes (67 MB) copied, 0.15139 s, 443 MB/s
Warning: The resulting partition is not properly aligned for best performance.
add map loop0p1 (252:2): 0 131071 linear /dev/loop0 1
mke2fs 1.42.12 (29-Aug-2014)
Discarding device blocks: done
Creating filesystem with 65532 1k blocks and 16384 inodes
Filesystem UUID: 2a52b053-c671-428d-bc13-6b967e0781c5
Superblock backups stored on blocks:
    8193, 24577, 40961, 57345

Allocating group tables: done
Writing inode tables: done
Writing superblocks and filesystem accounting information: done

Installing for i386-pc platform.
grub-install: warning: this msdos-style partition label has no post-MBR gap; embedding won't be possible.
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.

시나리오 2: dd count=256일 때 GRUB 성공

(venv3.4)root@userver:/home/ubuntu/ubuntucore# cat tst.sh
sudo dd if=/dev/zero of=./test.img oflag=direct bs=1M count=256
sudo mkdir -p /mnt/build
sudo parted -s test.img mklabel msdos
sudo parted -s -a optimal test.img mkpart primary ext2 '0%' '100%'
sudo parted -s test.img set 1 boot on
sudo kpartx -av test.img
sudo mke2fs -L '/' -t ext2 /dev/mapper/loop0p1
sudo mount /dev/mapper/loop0p1 /mnt/build
sudo grub-install --root-directory=/mnt/build /dev/loop0

# release mount
sudo umount -l /mnt/build
# release loopback
sudo dmsetup remove loop0p1
sudo losetup -d /dev/loop0

(venv3.4)root@server:/home/ubuntu/ubuntucore# . tst.sh
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 0.637421 s, 421 MB/s
add map loop0p1 (252:2): 0 522240 linear /dev/loop0 2048
mke2fs 1.42.12 (29-Aug-2014)
Discarding device blocks: done
Creating filesystem with 261120 1k blocks and 65280 inodes
Filesystem UUID: 1bf70e68-8f27-426d-b66e-c9c90aaa01b4
Superblock backups stored on blocks:
    8193, 24577, 40961, 57345, 73729, 204801, 221185

Allocating group tables: done
Writing inode tables: done
Writing superblocks and filesystem accounting information: done

Installing for i386-pc platform.
Installation finished. No error reported.