ec2/ecs resize2fs

If you have used a snapshot to create the EBS or with certain AMIs you will need to extend the disk (xvda), extend the partition (xvda1), then extend the filesystem (/).

If I'm reading this correctly, your disk looks like this:

/dev/xvda
|__/dev/xvda1__|______________ Free space______________|

It needs to look like this:

/dev/xvda
|______________________/dev/xvda1______________________|

After that, running resize2fs will grow into that new space within xvda1, using fdisk we can increase the block size by deleting and creating it again and making the partition bootable. all it requires is a reboot. In most cases it shouldn't effect your data if you use same start cylinder but Note that any mistake in recreating the partion will result in losing all data and/or the server will not reboot. I would recommend doing this as the first step on a newly created instance. Otherwise take a snapshot of your EC2 EBS Storage/etc.

I have marked the steps with <<#>> in the block below, so the are not a part of the command. You need root permissions, so do a "sudo sh" if you are not root.

<<1>> Look at the filesystem, it is 6G
<<2>> Look at the disk and the partition, the disk is 21.5 GB but the partition is 6 GB (6291456 blocks)
<<3>> Start fdisk for that disk (xvda, so not the partition xvda1)
<<4>> Switch to sector display.
<<5>> Print the partition(s), and remember the start sector (2048 in the example).
<<6>> Delete the partition.
<<7>> Create a new partition.
<<8>> Make it primary.
<<9>> First partition.
<<10>> Enter the old start sector, do NOT make any typo here!!! (2048 in the example) 
<<11>> Hit enter to accept the default (this is the remainder of the disk)
<<12>> Print the changes and make sure the start sector is ok, if not restart at <<6>>
<<13>> Make the partition bootable. do NOT forget this!!!
<<14>> Enter your partition number (1 in the example)
<<15>> Write the partition info back, this will end the fdisk session.
<<16>> Reboot the server, and wait for it to come up (this may take longer than usual).
<<17>> Verify the filesystem size.
<<18>> If the filesystem is not around 20Gb as expected, you can use this command.


# df -h  <<1>>

Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1      6.0G  2.0G  3.7G  35% / 
tmpfs            15G     0   15G   0% /dev/shm

# fdisk -l  <<2>>

Disk /dev/xvda: 21.5 GB, 21474836480 bytes
97 heads, 17 sectors/track, 25435 cylinders
Units = cylinders of 1649 * 512 = 844288 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0003b587

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           2        7632     6291456   83  Linux

# fdisk /dev/xvda  <<3>>

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): u  <<4>>
Changing display/entry units to sectors

Command (m for help): p  <<5>>

Disk /dev/xvda: 21.5 GB, 21474836480 bytes
97 heads, 17 sectors/track, 25435 cylinders, total 41943040 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 identifier: 0x0003b587

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *        2048    12584959     6291456   83  Linux

Command (m for help): d  <<6>>
Selected partition 1

Command (m for help): n  <<7>>
Command action
   e   extended
   p   primary partition (1-4)
p  <<8>>
Partition number (1-4): 1  <<9>>
First sector (17-41943039, default 17): 2048  <<10>>
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): <<11>>
Using default value 41943039

Command (m for help): p <<12>>

Disk /dev/xvda: 21.5 GB, 21474836480 bytes
97 heads, 17 sectors/track, 25435 cylinders, total 41943040 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 identifier: 0x0003b587

    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1            2048    41943039    20970496   83  Linux

Command (m for help): a  <<13>>
Partition number (1-4): 1  <<14>>


Command (m for help): w  <<15>>
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: ...
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

# reboot  <<16>>



# df -h  <<17>>
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1       20G  2.0G   17G  11% / 
tmpfs            15G     0   15G   0% /dev/shm

# resize2fs /dev/xvda1  <<18>>
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/xvda1 is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/xvda1 to 5242624 (4k) blocks.
The filesystem on /dev/xvda1 is now 5242624 blocks long.

root@vs120 [~]#  df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1       20G  7.8G   11G  42% /
tmpfs           498M     0  498M   0% /dev/shm
/usr/tmpDSK     399M   11M  368M   3% /tmp
root@vs120 [~]#
# xfs
xfs_growfs /dev/xvda1

Use the lsblk command to list the block devices attached to your instance. The example below shows three volumes: /dev/xvda, /dev/xvdb, and /dev/xvdf.

[ec2-user ~]$ lsblk
NAME    MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda    202:0    0  30G  0 disk
└─xvda1 202:1    0  30G  0 part /
xvdb    202:16   0  30G  0 disk /mnt
xvdf    202:80   0  35G  0 disk
└─xvdf1 202:81   0   8G  0 part

links:

https://serverfault.com/questions/414983/ec2-drive-not-ebs-volume-size

https://docs.aws.amazon.com/zh_cn/AWSEC2/latest/UserGuide/recognize-expanded-volume-linux.html

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