ext2 support? - G Tablet Q&A, Help & Troubleshooting

Specifically, what do I need to install on my gtab so that it can read an sdcard formatted to ext2?
I've already installed Clockworkmod and Vegan-Tab Ginger. Maybe I need a different kernel too? I know very little about kernels - Are they device specific? Are they interchangeable? Can I change the kernel without wiping my files?
Has anyone ever had success with ext2 on the gtab?

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deadfraggle said:
Specifically, what do I need to install on my gtab so that it can read an sdcard formatted to ext2?
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Nothing.
I know very little about kernels - Are they device specific?
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They have to be--that's their function after all.
Are they interchangeable?
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They should be. For the gTablet, you can use either the Clemsyn or Pershoot kernels. Both have native extn support.
Can I change the kernel without wiping my files?
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Yes.
Has anyone ever had success with ext2 on the gtab?
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ext2/3/4 are all natively supported by the linux kernel, and issuing a mount command will work if you do it on the command line. However, the automounter program, called vold, likes to have ext4 or VFAT (aka FAT32) filesystems on the SD card. If your ext2 formatted SD card is not automatically mounted, format it again as ext4.

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Formatted the sdcard to ext4, but still cannot read anything off it.
As for mounting through the terminal, if I use
fdisk -l
it shows nothing, not even an error. Is there another way to list disks so I know what to mount?
What I'm trying to do is use the Debian installer for Android, but the only version I could find is 2 years old. It's probably based on Lenny or earlier which does not have native ext4 support.

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deadfraggle said:
Formatted the sdcard to ext4, but still cannot read anything off it.
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What ROM are you on? Are you running Android or something else?
As for mounting through the terminal, if I use
fdisk -l
it shows nothing, not even an error. Is there another way to list disks so I know what to mount?
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Code:
$ su
# /system/xbin/fdisk -l /dev/block/mmcblk3
Disk /dev/block/mmcblk3: 16.0 GB, 16097738752 bytes
255 heads, 63 sectors/track, 1957 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/block/mmcblk3p1 1 1709 13720703 c Win95 FAT32 (LBA)
/dev/block/mmcblk3p2 1709 1958 1999744+ 83 Linux
Use /dev/block/mmcblk2 for the external SD card. Mount it as:
Code:
$ su
# mount /dev/block/mmcblk2p1 /some/path
or
Code:
$ su
# mount -t ext4 /dev/block/mmcblk2p2 /some/path

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rajeevvp said:
What ROM are you on? Are you running Android or something else?
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Vegan-Tab Ginger edition
rajeevvp said:
Code:
$ su
# /system/xbin/fdisk -l /dev/block/mmcblk3
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This gives me similar results to yours.
rajeevvp said:
Use /dev/block/mmcblk2 for the external SD card. Mount it as:
Code:
$ su
# mount /dev/block/mmcblk2p1 /some/path
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My result:
Code:
$ su
# mount /dev/block/mmcblk2p1 /micro
mount: mounting /dev/block/mmcblk2p1 on /micro failed: No Such file or directory
Also tried
mount /dev/block/mmcblk2p2 /micro
with the same result.
rajeevvp said:
or
Code:
$ su
# mount -t ext4 /dev/block/mmcblk2p2 /some/path
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My result:
Code:
$ su
# mount -t ext4 /dev/block/mmcblk2p2 /micro
mount: mounting /dev/block/mmcblk2p2 on /micro failed: No Such file or directory
Edit:
If I insert a ext2 formatted sdcard, I get a notice that it is being scanned for errors. It goes away after a minute or so.
If I go to /sdcard2 in Root Explorer, the folder is empty but the stats show a correct 2 gb of used space and the correct amount of free space.
(Also in Root Explorer, if I try to create a test file, it says 'successful' but no file is created.)
If someone here owns a gtab and can access a ext2/4 sdcard, please let me know what setup/Rom you are using. Or if you own an extra sdcard you can format to ext2, and use some other aftermarket ROM/different kernel on your gtab, please test and post your results.

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The commands I gave were just examples, you'll have to adjust them to suit your system.
deadfraggle said:
If I insert a ext2 formatted sdcard, I get a notice that it is being scanned for errors. It goes away after a minute or so.
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That looks like the correct behaviour. The external SD card is being fsck'd and then automounted.
If I go to /sdcard2 in Root Explorer, the folder is empty but the stats show a correct 2 gb of used space and the correct amount of free space.
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This, again, is correct, except that on a newly created filesystem, Root Explorer should've shown a lost+found directory.
(Also in Root Explorer, if I try to create a test file, it says 'successful' but no file is created.)
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Reformat the filesystem again and try creating a file using the command line:
Code:
$ su
# echo test > /mnt/sdcard2/test.txt
# cat /mnt/sdcard2/test.txt
test
#
My external SD card is formatted as ext3 and I have no problem using Root Explorer. With other file managers, you'll have to be careful because of the standard Unix permissions that come into effect on all extn filesystems. If you want to use file managers other than Root Explorer, just create a new directory on your ext2 filesystem and give that directory a user of "system" and a group of "sdcard_rw", and give (at least) the group "rwx" permissions. Use the user, group and permissions of the /mnt/sdcard directory as a guide:
Code:
$ ls -ld /mnt/sdcard
d---rwxr-x 22 system sdcard_rw 8192 Jan 1 1970 /mnt/sdcard
$ su
# mkdir /mnt/sdcard2/user-dir
# chmod 0775 /mnt/sdcard2/user-dir [I]#or 0075 to exactly match /mnt/sdcard[/I]
# chown system.sdcard_rw /mnt/sdcard2/user-dir
If you don't want to bother with all this, just format the SD card as VFAT, and Android will automatically mount the VFAT filesystem with an owner of "system" and a group of "sdcard_rw". And since (all?) file managers belong to the "sdcard_rw" group, they get automatic read-write permissions to that filesystem. BTW, the Terminal Emulator app also belongs to the "sdcard_rw" group, so you can freely write onto VFAT formatted SD cards on the command line without resorting to the 'su' command (the example above).

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Granted, it's been a while since I researched this - but I learned many months ago that the version of VOLD in Froyo does not support anything else but vFAT - so it just won't mount EXT2, or NTFS for that matter.
the mount command would bypass VOLD and we know that NTFS should work, if it's a custom kernel. Conceivably EXT2 should also work, but since it was all manual scripting I just stopped researching it - mainly because I'd still have issues using the card with other devices so it wouldn't really be a portable solution anymore.
As much as I detest FAT32 for its file size limitations, it's still the "standard" between portable devices. The various vendors have yet to figure out a replacement, since they can't seem to agree on anything.

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rajeevvp said:
My external SD card is formatted as ext3 and I have no problem using Root Explorer.
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Figures. Never tried ext3, mainly because it's not a readily available option in Ubuntu. Tried to format to ext3 via the terminal but got a weird error, even after unmounting the drive:
"/dev/sdb is apparently in use by the system; will not make a filesystem here!"
So I booted in to Parted Magic with my netbook, wiped the sdcard, and created a new ext3 partition.
Success!!
The sdcard auto-mounts, and is accessible by Root Explorer, ES File Explorer and File Manager.
Ext3 will suit my purposes just fine. Sorry to make you write all the rest of your post, but it will be a handy reference.
Thank you a million times over!
@ roebeet
I'm humbled this post got your attention. Thanks for the great work!

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deadfraggle said:
Figures. Never tried ext3, mainly because it's not a readily available option in Ubuntu.
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The ext3 format was the default filesystem of Ubuntu, until just recently. It is generally considered better to use ext2 on a SD card. Since a SD card has a limited number of read/writes, a journaling filesystem like ext3/ext4 would use up the limited number of read/writes faster than using ext2. Also, never create a swap partition on a flash drive or SD card.
To format a SD card in Ubuntu, first determine the device name:
Code:
[email protected]:~$ sudo fdisk -l
[sudo] password for paul:
Disk /dev/sda: 64.6 GB, 64609058816 bytes
255 heads, 63 sectors/track, 7854 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000d996
Device Boot Start End Blocks Id System
/dev/sda1 * 1 3890 31246393+ 83 Linux
/dev/sda2 3891 7854 31840830 83 Linux
Disk /dev/sdb: 16.4 GB, 16437477376 bytes
255 heads, 63 sectors/track, 1998 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b3366
Device Boot Start End Blocks Id System
/dev/sdb1 1 1998 16048903+ 83 Linux
My EEEPC has a 64 GB hard drive, and a 16 GB SDHC card. So the card I want to format is /dev/sdb1. Use fdisk again for the formatting, here are the steps copied directly from my terminal:
Run commands with root privileges (sudo).
Find the disk:
# sudo fdisk -l
Format the disk (sdb1):
# sudo fdisk /dev/sdb1
Command (m for help):d (delete any existing partitions)
Command (m for help):n (create a new partition)
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4):1
Command (m for help):w (to write the changes to the disk)
Format the card. You may need to unmount it first:
# sudo umount /dev/sdb1
# sudo mkfs -t ext3 /dev/sdb1