unable to resize root partition on EC2 centos

Question

I created my EC2 Machine using Community Image of Centos 6.3 x64. I have added a 35 GB disk. Now when I do #df -h

Filesystem            Size Used Avail Use% Mounted on

/dev/xvda1            7.9G 1.2G 6.4G 16% /

tmpfs                 7.3G 0 7.3G 0% /dev/shm

my disk is 35GB but it's showing 8 GB in root and 7 as tmpfs.

I tried to use resize2fs but it didn't work on centos. the disk has an ext4 partition.

# resize2fs /dev/xvda

resize2fs 1.41.12 (17-May-2010)

resize2fs: Device or resource busy while trying to open /dev/xvda

Couldn't find valid filesystem superblock.

or even if I tried resize2fs /dev/xvda1 it says the device has nothing to do.

any idea or another way, it's my root disk(/), so can’t unmount it.

Answer 1

To do this, increase your block size by deleting and recreating it band also making the partition bootable. There won't be any effect on your data if you use the same start cylinder.

Got the answer from this AWS forum section. https://forums.aws.amazon.com/thread.jspa?messageID=547507

The numbers, for example "<<1>>" are steps.

The answer:

# 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: Device or resource busy.

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>>

<wait>

# 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)

The filesystem is already 5242624 blocks long.  Nothing to do!