lvm简单使用以及grub2菜单不显示的解决方法

lvm 的简单使用

因为lvextend扩展的是lv, df看到的是文件系统，所以调整分区后 df 和 lsblk 的结果可能不一致
若调整分区后 df 和 lsblk 的结果不一致，使用 resize2fs -p -F /dev/part 进行文件系统的调整

root@server1804:~# resize2fs -p -F /dev/mapper/ubuntu--vg-ubuntu--lv
resize2fs 1.44.1 (24-Mar-2018)
Filesystem at /dev/mapper/ubuntu--vg-ubuntu--lv is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 2
The filesystem on /dev/mapper/ubuntu--vg-ubuntu--lv is now 2621440 (4k) blocks long.

root@server1804:~#

扩容

1. 增加到10G：lvextend -L 10G /dev/ubuntu-vg/ubuntu-lv
2. 增加10G：lvextend -L +10G /dev/ubuntu-vg/ubuntu-lv

root@server1804:~# lvextend -L 10G /dev/ubuntu-vg/ubuntu-lv
  Size of logical volume ubuntu-vg/ubuntu-lv changed from 4.00 GiB (1024 extents) to 10.00 GiB (2560 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.
root@server1804:~#

减少

1. 减少到10G：lvextend -L 10G /dev/ubuntu-vg/ubuntu-lv
2. 减少10G：lvextend -L -10G /dev/ubuntu-vg/ubuntu-lv

root@server1804:~# lvreduce -L -1G /dev/ubuntu-vg/ubuntu-lv
  WARNING: Reducing active and open logical volume to 10.00 GiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce ubuntu-vg/ubuntu-lv? [y/n]: y
  Size of logical volume ubuntu-vg/ubuntu-lv changed from 11.00 GiB (2816 extents) to 10.00 GiB (2560 extents).
  Logical volume ubuntu-vg/ubuntu-lv successfully resized.
root@server1804:~#

grub2 菜单不显示

若要使修改生效，必须 update-grub

1. 保证 grub 延迟不为零
2. 延迟等待样式不为 hidden

• 修改 /etc/default/grub: vim /etc/default/grub

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="debian-installer/custom-installation=/custom find_preseed=/preseed.cfg auto preseed/file=/floppy/preseed.cfg automatic-ubiquity noprompt priority=critical locale=en_US console-setup/modelcode=evdev"
GRUB_CMDLINE_LINUX=""

• 将 GRUB_TIMEOUT_STYLE=hidden 修改为 GRUB_TIMEOUT_STYLE=menu 且 GRUB_TIMEOUT 不为零。

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="debian-installer/custom-installation=/custom find_preseed=/preseed.cfg auto preseed/file=/floppy/preseed.cfg automatic-ubiquity noprompt priority=critical locale=en_US console-setup/modelcode=evdev"
GRUB_CMDLINE_LINUX=""