最近花150r搞了个2年的迷你主机，0.5C 0.5G + 20G 硬盘，虽然性能拉胯但1G带宽每月1T流量，倒也还行，装个Alpine还是绰绰有余的
主机装上系统一看，根目录/才1个多G，我就纳闷了，不是20G么，本来想提单但想想应该是软件问题，先用fdisk -l看一下
# fdisk -l
Disk /dev/vda: 20 GB, 21474836480 bytes, 41943040 sectors
41610 cylinders, 16 heads, 63 sectors/track
Units: sectors of 1 * 512 = 512 bytes
Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type
/dev/vda1 * 2,0,33 205,3,19 2048 206847 204800 100M 83 Linux
/dev/vda2 205,3,20 1023,15,63 206848 1255423 1048576 512M 82 Linux swap
/dev/vda3 1023,15,63 1023,15,63 1255424 4194303 2938880 1435M 83 Linux合着还有18G根本没分配，那重新分个区就好了，先把要用的软件安装上
# apk add e2fsprogs-extra 用fdisk进入磁盘管理界面
# fdisk /dev/vda
The number of cylinders for this disk is set to 41610.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)输入d选择删掉分区，输入3选择vda3（根目录）
Command (m for help): d
Partition number (1-4): 3然后输入n新建分区，p选择基本分区，3代表vda3
Command (m for help): n
Partition type
p primary partition (1-4)
e extended
p
Partition number (1-4): 3然后输入起始扇区，就是在之前通过fdsik -l看到的vda3起始扇区，也就是StartLBA，这里输入1255424，然后结束扇区默认就是最后一个扇区，也就是全部分配给vda3，当然也可以自定义分配多少
First sector (63-41943039, default 63): 1255424
Last sector or +size{,K,M,G,T} (1255424-41943039, default 41943039):
Using default value 41943039这时就分配完毕了，输入p查看现在分区状态
Command (m for help): p
Disk /dev/vda: 20 GB, 21474836480 bytes, 41943040 sectors
41610 cylinders, 16 heads, 63 sectors/track
Units: sectors of 1 * 512 = 512 bytes
Device Boot StartCHS EndCHS StartLBA EndLBA Sectors Size Id Type
/dev/vda1 * 2,0,33 205,3,19 2048 206847 204800 100M 83 Linux
/dev/vda2 205,3,20 1023,15,63 206848 1255423 1048576 512M 82 Linux swap
/dev/vda3 1023,15,63 1023,15,63 1255424 41943039 40687616 19.4G 83 Linux可以看到vda3已经扩容了，输入w保存
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table
fdisk: WARNING: rereading partition table failed, kernel still uses old table: Resource busy警告直接无视，使用partprobe刷新分区表
# partprobe /dev/vda再使用resize2fs（针对ext4文件系统）给vda3扩容
# resize2fs /dev/vda3
resize2fs 1.46.6 (1-Feb-2023)
Filesystem at /dev/vda3 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 3
The filesystem on /dev/vda3 is now 5085952 (4k) blocks long.这下就扩容完毕了，使用df -h看看
# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 10M 0 10M 0% /dev
shm 241M 0 241M 0% /dev/shm
/dev/vda3 20G 188M 19G 2% /
tmpfs 97M 128K 97M 1% /run
/dev/vda1 89M 18M 64M 22% /boot
tmpfs 241M 0 241M 0% /tmp大功告成