ESXI(VMware)里linux系统的磁盘空间有点不够用了，所以要扩容一下。它不像Windows系统那样简单的点几下鼠标就完成扩容了。这里简单记录一下操作过程。
首先关闭linux虚拟机，然后进入ESXI, 编辑虚拟机, 直接修改硬盘大小, 这里原先是50GB，直接设置到100GB。然后启动linux虚拟机后进入系统，
首先查看挂载点和文件系统类型，
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alovn@ubuntu-desktop:~$ df -Th
Filesystem Type Size Used Avail Use% Mounted on
tmpfs tmpfs 1.6G 1.7M 1.6G 1% /run
/dev/sda3 ext4 98G 15G 80G 16% /
tmpfs tmpfs 7.9G 36M 7.8G 1% /dev/shm
tmpfs tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/sda2 vfat 512M 6.1M 506M 2% /boot/efi
tmpfs tmpfs 1.6G 2.4M 1.6G 1% /run/user/1000
比如这里要对根分区/进行扩容， 可以看到磁盘文件分区是 /dev/sda3，文件系统类型是ext4。
然后查看磁盘分区情况
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alovn@ubuntu-desktop:~$ sudo fdisk -l
Disk /dev/sda: 100 GiB, 107374182400 bytes, 209715200 sectors
Disk model: Virtual disk
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D08810AD-21EF-431A-9B8E-481245778CB1
Device Start End Sectors Size Type
/dev/sda1 2048 4095 2048 1M BIOS boot
/dev/sda2 4096 1054719 1050624 513M EFI System
/dev/sda3 1054720 105906176 104851456 50 Linux filesystem
可以看到磁盘 /dev/sda 共有100GB， /dev/sda3 使用了50GB, 还有大约50GB。
使用 fdisk 修改分区大小:
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alovn@ubuntu-desktop:~$ sudo fdisk /dev/sda
Welcome to fdisk (util-linux 2.37.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
This disk is currently in use - repartitioning is probably a bad idea.
It's recommended to umount all file systems, and swapoff all swap
partitions on this disk.
Command (m for help): m # 键入m, 查看命令帮助
Help:
GPT
M enter protective/hybrid MBR
Generic
d delete a partition
F list free unpartitioned space
l list known partition types
n add a new partition
p print the partition table
t change a partition type
v verify the partition table
i print information about a partition
Misc
m print this menu
x extra functionality (experts only)
Script
I load disk layout from sfdisk script file
O dump disk layout to sfdisk script file
Save & Exit
w write table to disk and exit
q quit without saving changes
Create a new label
g create a new empty GPT partition table
G create a new empty SGI (IRIX) partition table
o create a new empty DOS partition table
s create a new empty Sun partition table
Command (m for help): d # 首先删除原来到分区
Partition number (1-3, default 3): 3 # 键入分区编号，这里是3
Partition 3 has been deleted.
Command (m for help): n # 新建分区
Partition number (3-128, default 3): 3 # 新建的分区编号，3
First sector (1054720-209715166, default 1054720): # 扇区开始位置，默认即可, 回车确认
Last sector, +/-sectors or +/-size{K,M,G,T,P} (1054720-209715166, default 209715166): # 扇区结束位置，默认全部分配，回车确认
Created a new partition 3 of type 'Linux filesystem' and of size 100 GiB.
Partition #3 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: y
The signature will be removed by a write command.
Command (m for help): p # 打印新的分区信息, 可以看到现在是100GB
Disk /dev/sda: 100 GiB, 107374182400 bytes, 209715200 sectors
Disk model: Virtual disk
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D08810AD-21EF-431A-9B8E-481245778CB1
Device Start End Sectors Size Type
/dev/sda1 2048 4095 2048 1M BIOS boot
/dev/sda2 4096 1054719 1050624 513M EFI System
/dev/sda3 1054720 209715166 208660447 100G Linux filesystem
Filesystem/RAID signature on partition 3 will be wiped.
Command (m for help): w # 保存分区信息
The partition table has been altered.
Syncing disks.
保存分区信息后，需要重启系统，执行 reboot。
重启之后需要执行 resize2fs 更新文件系统的大小：
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alovn@ubuntu-desktop:$ sudo resize2fs /dev/sda3
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/sda3 is mounted on /; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 13
The filesystem on /dev/sda3 is now 26082555 (4k) blocks long.
再次查看分区信息：
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alovn@ubuntu-desktop:~$ sudo fdisk -l
Disk /dev/sda: 100 GiB, 107374182400 bytes, 209715200 sectors
Disk model: Virtual disk
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D08810AD-21EF-431A-9B8E-481245778CB1
Device Start End Sectors Size Type
/dev/sda1 2048 4095 2048 1M BIOS boot
/dev/sda2 4096 1054719 1050624 513M EFI System
/dev/sda3 1054720 209715166 208660447 100G Linux filesystem
alovn@ubuntu-desktop:~$ df -Th
Filesystem Type Size Used Avail Use% Mounted on
tmpfs tmpfs 1.6G 1.7M 1.6G 1% /run
/dev/sda3 ext4 98G 15G 80G 16% /
tmpfs tmpfs 7.9G 52M 7.8G 1% /dev/shm
tmpfs tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/sda2 vfat 512M 6.1M 506M 2% /boot/efi
tmpfs tmpfs 1.6G 2.4M 1.6G 1% /run/user/1000
到这里扩容已经完成了。
注意：如果你的linux磁盘扩容后，发现使用fdisk查看磁盘分区已经扩容成功，而用df查看文件系统大小却没有变化，那么可能是你重启后忘记执行上面的 resize2fs 命令了。这是因为fdisk查看的是磁盘大小，而df查看的是文件系统大小，两者是有区别的。
resize2fs 用于扩展文件系统的逻辑边界， 它适用于 ext2、ext3、ext4文件系统，如果是xfs文件系统，则需要使用 xfs_growfs。