I have tested the procedure using qemu-kvm.
qemu-kvm -boot once=d -cdrom CentOS-6.7-i386-LiveCD.iso -hda centos_2G.img -m 2G
Using a live CD image, to do the resizing, and a USB flash disk image as the test subject.
The general procedure described for doing this is as below -
Check that filesystem is OK
e2fsck /dev/sda1
Use fdisk to delete and recreate the partition, in place, but with increased size
fdisk /dev/sda
p - to show table, note details
d - to delete partition
n - to create new partition, using details from before, increasing the end block as needed
a - to toggle boot flag
w - to write partition table back to disk
Re-check that filesystem is OK
e2fsck /dev/sda1
At this point the process fails for me, with the error -
Superblock invalid
Bad magic number in super-block
and from here I have not found a way to recover the filesystem.
I have tried a similar process using parted, and also failed.
Using gdisk (GPT) instead of fdisk
[root@livecd ~]# e2fsck /dev/sda1
e2fsck 1.41.12 (17-May-2010)
/dev/sda1: clean, 18823/65536 files, 209783/261888 blocks
[root@livecd ~]# yum install gdisk
[root@livecd ~]# gdisk /dev/sda
GPT fdisk (gdisk) version 0.8.10
Partition table scan:
MBR: MBR only
BSD: not present
APM: not present
GPT: not present
***************************************************************
Found invalid GPT and valid MBR; converting MBR to GPT format
in memory. THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by
typing 'q' if you don't want to convert your MBR partitions
to GPT format!
***************************************************************
Command (? for help): p
Disk /dev/sda: 3913728 sectors, 1.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): F2EA2B62-4D1C-4D0A-8274-24009DC5353D
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 3913694
Partitions will be aligned on 2048-sector boundaries
Total free space is 1818557 sectors (888.0 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 2097151 1023.0 MiB 8300 Linux filesystem
Command (? for help): d
Using 1
Command (? for help): n
Partition number (1-128, default 1):
First sector (34-3913694, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-3913694, default = 3913694) or {+-}size{KMGTP}: 1700M
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300):
Changed type of partition to 'Linux filesystem'
Command (? for help): x
Expert command (? for help): a
Using 1
Known attributes are:
0: system partition
1: hide from EFI
2: legacy BIOS bootable
60: read-only
62: hidden
63: do not automount
Attribute value is 0000000000000000. Set fields are:
No fields set
Toggle which attribute field (0-63, 64 or to exit): 2
Have enabled the 'legacy BIOS bootable' attribute.
Attribute value is 0000000000000004. Set fields are:
2 (legacy BIOS bootable)
Toggle which attribute field (0-63, 64 or to exit):
Expert command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/sda.
The operation has completed successfully.
[root@livecd ~]# e2fsck -f /dev/sda1
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 3A: Optimizing directories
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/sda1: ***** FILE SYSTEM WAS MODIFIED *****
/dev/sda1: 18823/65536 files (0.7% non-contiguous), 209783/261888 blocks
[root@livecd ~]# resize2fs /dev/sda1
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/sda1 to 434944 (4k) blocks.
The filesystem on /dev/sda1 is now 434944 blocks long.
[root@livecd ~]# e2fsck /dev/sda1
e2fsck 1.41.12 (17-May-2010)
/dev/sda1: clean, 18823/114688 files, 212932/434944 blocks
All good, now reboot, and see that the image boots successfully.
[root@usbhda ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 1.7G 804M 783M 51% /
tmpfs 947M 0 947M 0% /dev/shm
