Resizing SD card via command line

[lumpynose]

Re-imaged my sd card (I'm doing this on a Raspberry Pi) and tried the above; the second part, the resizing with resize2fs fails because the filesystem is mounted read only and it complains about that. The man page for resize2fs says
$this->bbcode_second_pass_quote('', '
')If the filesystem is mounted, it can be used to expand the size of the mounted filesystem, assuming the kernel supports on-line resizing. (As of this writing, the Linux 2.6 kernel supports on-line resize for filesystems mounted using ext3 and ext4).

[pepedog]

I was dubious this could be done on a mounted system, but it works.
There may be complaints that e2fsck has to be run before or after resize, that works too

[lumpynose]

Here are my latest notes to myself. I've added some reboots and going to single user mode because I'm paranoid:

Before running fdisk I brought the system down to single user and remounted the root partition read-only. In the following the # is root’s prompt.

# systemctl rescue
# mount -o ro,remount /
# fdisk /dev/mmcblk0

Delete the second partition /dev/mmcblk0p2.

d
2

Create a new primary partition and use default sizes prompted. This will then create a partiton that fills the disk.

n
p
2
enter
enter

Save and exit fdisk:

w

Reboot and run resize2fs:

# shutdown -r now
# systemctl rescue
# resize2fs /dev/mmcblk0p2

Your main / partition should be the full size of the disk now. Don’t remount the root partition read-only before you run resize2fs; resize2fs fails if it’s mounted read-only.

After running resize2fs reboot, go to single user, remount root read-only, and run e2fsck:

# shutdown -r now
# systemctl rescue
# mount -o ro,remount /
# e2fsck /dev/mmcblk0p2
# shutdown -r now

[pepedog]

One step I would encourage is before # shutdown -r now, or reboot or poweroff, use sync command

[lumpynose]

$this->bbcode_second_pass_quote('pepedog', 'O')ne step I would encourage is before # shutdown -r now, or reboot or poweroff, use sync command

$this->bbcode_second_pass_quote('lumpynose', '')$this->bbcode_second_pass_quote('pepedog', 'O')ne step I would encourage is before # shutdown -r now, or reboot or poweroff, use sync command

[pepedog]

Which of all those options, including poweroff, turns off most LEDs?
I think sync is flaky with all shutdown methods (all distro), especially where fat is concerned.
Might seem paranoid but I have seen instructions for untarring rootfs and it ends with
$this->bbcode_second_pass_code('', 'sync
sync
sync
sleep 3
halt')
So you make up your mind on that
I have had a pi for 16 months, never had corruption, and always synced. Search posts in Raspberry Pi forum and see how many point to sync as "Solved" soloution

[lumpynose]

It actually depends on the phase of the moon, and sometimes the date. When the moon is waxing you only need 2 syncs. When it's waning you need the 3 syncs. On February 29th you need another sync after the sleep.

[jawbonegroove]

excellent post. can we get this sticky'd...?

[paranoidandroid]

I have tried this on the latest release (archlinux-hf-2013-07-22.img) and the geometry has changed, the disk now has an extended partition with a logical one inside that…

fdisk reports (after imaging onto 8GB card)
$this->bbcode_second_pass_code('', ' Device Boot Start End Blocks Id System
/dev/mmcblk0p1 2048 186367 92160 c W95 FAT32 (LBA)
/dev/mmcblk0p2 186368 3667967 1740800 5 Extended
/dev/mmcblk0p5 188416 3667967 1739776 83 Linux
')

It looks like both the extended & logical partitions need to be deleted (p2 and p5)

Something like…
$this->bbcode_second_pass_code('', '
fdisk "/dev/mmcblk0"
p
d
2
n
e
(return) # accept default partition no
(return) # accept default start
(return) # accept default end
n
l
(return) # accept default start
(return) # accept default end
p
w

sync; reboot
...
resize2fs /dev/mmcblk0p5
fsck etc
')

I get the following geometry from fdisk…
$this->bbcode_second_pass_code('', '
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 2048 186367 92160 c W95 FAT32 (LBA)
/dev/mmcblk0p2 186368 15652863 7733248 5 Extended
/dev/mmcblk0p5 188416 15652863 7732224 83 Linux
')


I tried only deleting the last partition but it is limited by the size of the enclosing extended partition, so you can't expand the partition until the extended one is also expanded.

Thanks for all the tips so far, this is handy - hope this helps too