Repartitioning 16GB SDHC back to FAT
 

After spending a whole night trying to get the latest OS2008 to boot from my MMC and failing miserably, I've decided to go back to booting from flash

However, I'm now stuck with a 16GB SDHC that Windows only recognizes as 14GB since there's a LINUX partition in there.

How do I repartition the SD back to a full FAT system?

I tried

sudo gainroot
umount /media/mmc2
sfdisk /dev/mmcblk0 -uM
1,,0C
<enter>
<enter>
<enter>

Then I get a message saying

Warning: No primary partition is marked bootable (active). This does not matter for LILO, but the DOS MBR will not boot this disk.

At which point I chickened out.

Rather than risk corrupting my SD beyond repair, what is the correct command to use to get this SD back to a full FAT system?

Re: Repartitioning 16GB SDHC back to FAT
 

That message is normal and expected. All that it means is that you can't install windows on it and expect to be able to boot your desktop off of it until you mark the partition as bootable.

-John

Re: Repartitioning 16GB SDHC back to FAT
 

I think maybe there is an easy way to re-partition it under windows.

1. Put the SD to the external slot of the N8x0
2. Connect the supplied cable from the windows PC and the N8x0
3. Right click on "My Computer" choose "Manage"
4. Click "Disk Management" to find the SD
5. Pay attention to the SD label,size,.... then select it to re-partion, format, ...

Re: Repartitioning 16GB SDHC back to FAT
 

Problem is, Windows Vista absolutely REFUSES to acknowledge the card. I tried it with another SD card that i use for trackday datalogging and that turned up fine.

John, if i proceed to format the card using those commands, then run mkdosfs on that partition, it should be readable from Windows again, right?

Re: Repartitioning 16GB SDHC back to FAT
 

Just ran the commands in my first post.

Internal memory card is no longer recognized by the tablet. How do I get it working again?

Urgent advise required, HELP!

Re: Repartitioning 16GB SDHC back to FAT
 

Put the card into your internal slot and do:
mkdosfs -F32 /dev/mmcblk0p1

If that doesn't work post the error message.

Re: Repartitioning 16GB SDHC back to FAT
 

Hi John

That seems to work -- the Memory applet now shows that i have 492.8MB available as 100% of my 16GB SDHC.

I have run an sfdisk -ls and it shows that /dev/mmcblk0p4 has somehow grabbed the remaining storage. Info from sfdisk is as follows:

/home/user # sfdisk -ls
/dev/mmcblk0: 15694336

Disk /dev/mmcblk0: 490448 cylinders, 4 heads, 16 sectors/track
Units = cylinders of 32768 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/mmcblk0p1 1 15800 15800 505600 c W95 FAT32 (LBA)
/dev/mmcblk0p2 0+ 0 1- 31+ 83 Linux
/dev/mmcblk0p3 15801 490447 474647 15188704 83 Linux
/dev/mmcblk0p4 0 - 0 0 0 Empty
/dev/mmcblk1: 123008

Disk /dev/mmcblk1: 3844 cylinders, 4 heads, 16 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/8/32 (instead of 3844/4/16).
For this listing I'll assume that geometry.
Units = cylinders of 131072 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/mmcblk1p1 0+ 960 961- 122959+ 6 FAT16
/dev/mmcblk1p2 0 - 0 0 0 Empty
/dev/mmcblk1p3 0 - 0 0 0 Empty
/dev/mmcblk1p4 0 - 0 0 0 Empty
total: 15817344 blocks

My external card is 128 MB and the internal is a 16GB SDHC

Thanks for the advice. Looking forward to getting things back to the way they were before I got ambitious.

Re: Repartitioning 16GB SDHC back to FAT
 

I had the same problem first time; I just did:

sudo gainroot
umount /media/mmc1 (I was using removable)
sfdisk /dev/mmcblk1
1,,6 (Or I think it was 1,6)

Sfdisk still listed a linux partition but it was only like 32KB so it wasn't worth the trouble trying to delete it.

I then did mkdosfs /dev/mmcblk1p1.

Re: Repartitioning 16GB SDHC back to FAT
 

That seems to work (it's 1,,6, btw), and I now have 14.63 GB back out of my 16GB Transcend SDHC card.

/home/user # sfdisk -ls
/dev/mmcblk0: 15694336

Disk /dev/mmcblk0: 490448 cylinders, 4 heads, 16 sectors/track
Units = cylinders of 32768 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/mmcblk0p1 1 490447 490447 15694304 6 FAT16
/dev/mmcblk0p2 0+ 0 1- 31+ 83 Linux
/dev/mmcblk0p3 0 - 0 0 0 Empty
/dev/mmcblk0p4 0 - 0 0 0 Empty
/dev/mmcblk1: 123008

Disk /dev/mmcblk1: 3844 cylinders, 4 heads, 16 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/8/32 (instead of 3844/4/16).
For this listing I'll assume that geometry.
Units = cylinders of 131072 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/mmcblk1p1 0+ 960 961- 122959+ 6 FAT16
/dev/mmcblk1p2 0 - 0 0 0 Empty
/dev/mmcblk1p3 0 - 0 0 0 Empty
/dev/mmcblk1p4 0 - 0 0 0 Empty
total: 15817344 blocks

Is anyone else using this Transcend SDHC card? If so, how much free space do you have off a freshly-formatted 16GB SDHC?

If you're ever in Dubai, I'm buying you a round!

Re: Repartitioning 16GB SDHC back to FAT
 

Hang on, it's saying FAT16.

It was LBA before -- do I need to reformat it for LBA or will a FAT16 be more efficient? Which is a more efficient filesystem?

Re: Repartitioning 16GB SDHC back to FAT
 

I think the partition is just marked FAT16 and the filesystem used is actually FAT32 since you can't really have a FAT16 partition over 2GB (or is it 4GB?). Glad you got it working at any rate.

-John

Re: Repartitioning 16GB SDHC back to FAT
 

FAT32 is needed for files up to 2TB (according to http://www.computerhope.com/fat32.htm), but I think it means GB (or am I mistaken)

FAT32 is supposed to use space more efficiently as well (up to 5%?)

Re: Repartitioning 16GB SDHC back to FAT
 

Format it in windows again, that should reformat it back to FAT32.

FAT32 is recommended IMHO for such a large amount.

The article must mean 2GB, FAT32 cannot create or have files over 4GB.

If you really can't get it back to FAT32,

I was editing while you were posting so you already did the above :D.

Re: Repartitioning 16GB SDHC back to FAT
 

Yeah, i just redid the steps you recommended and went for 1,,0C and it became W95 WBA, and it's now 14.95GB instead of 14.63GB :D

Thanks a million!

(maybe someone needs to add this 'recovery steps' for people who mess up their SD/MMCs in the quest to boot from SD/MMC

While I would love to have the extra performance (which I understand comes from the application files being uncompressed in the first place) that comes with booting from SD/MMC, I don't think I could live with the grief of having to deal with more X-Term every time i need to connect the device via USB to my XP desktop

Re: Repartitioning 16GB SDHC back to FAT
 

Cool, I'm glad it all worked out for you :)

As long as it's orange juice or lemonade :P :D

Re: Repartitioning 16GB SDHC back to FAT
 

Couldn't have done it if you didn't set me back on the right path. I now understand that

x,y,z means

x= start address block
y= end address block
z = file system type (6 = FAT16, 0C = W95 FAT WBA, not sure what Linux is)

Strangely enough, when I partitioned my system the first time using:

1,14000,0C
,,,

followed by

mkdosfs /dev/mmcblk0p1
mke2fs /dev/mmcblk0p2

Control panel -> Memory only showed that I had 473MB of space available.

I'm assuming that the Memory applet shows the FAT memory, so I can't explain why it was showing the storage memory allocated to Linux.

Did I get them mixed up and should have used

mkdosfs /dev/mmcblk0p2
mke2fs /dev/mmcblk0p1

instead?

Re: Repartitioning 16GB SDHC back to FAT
 

I'm sure

was right as the ext2fs partition is created anyway on the second partition.

I think the Memory applet shows the memory of whatever partition is mounted. It seems like sfdisk was (partly?) mounting the partitions because whenever I would run it, it would show memory card available which is the message I get when I mount a card.

Re: Repartitioning 16GB SDHC back to FAT
 

So what you're saying is that the Memory applet was correct is showing me the amount of space in internal memory?

Mine was looking something like this (http://www.internettablettalk.com/fo...&postcount=242) when I opened the Memory applet after partitioning and running

./nupgrade.sh 0
./nupgrade.sh 1
./nupgrade.sh 2
./nupgrade.sh 3
./nupgrade.sh 4
reboot

except that I had 473MB of storage space instead of the 4.87 GB that dan had.

Seeing that I had tried to partition for 14GB of FAT storage and .95GB (or so) of Linux strorage, I had expected device memory to be in the region of 300+ MB, and internal storage to be in the region of 14GB

I still haven't figured out where I went wrong.

Re: Repartitioning 16GB SDHC back to FAT
 

Actually it could have done, because the 0 option mounts the extfs2 partition.

I wanted the same sort of thing (more space to the FAT partition and less to linux but guides on here assume you want more space on the Linux partition).

So I just did the amount of space I wanted for the linux partition (300MB) 300x32=9600 and when I ran sfdisk, I checked the number of cylinders (sfdisk tells you when you run it) on the 1st partition (which was originally using all the MMC card) and subtracted 9600 from the value sfdisk gave me and used that value to make my FAT partition and then done the use free space linux partition.

Re: Repartitioning 16GB SDHC back to FAT
 

Just partitioned again, and rebooted, the gainroot-ed and sfdisk -ls and got this:

/home/user # sfdisk -ls
/dev/mmcblk0: 15694336

Disk /dev/mmcblk0: 490448 cylinders, 4 heads, 16 sectors/track
Units = cylinders of 32768 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/mmcblk0p1 32 448031 448000 14336000 c W95 FAT32 (LBA)
/dev/mmcblk0p2 0+ 31 32- 1023+ 83 Linux
/dev/mmcblk0p3 448032 490447 42416 1357312 83 Linux
/dev/mmcblk0p4 0 - 0 0 0 Empty
total: 15694336 blocks

How did the 1GB I allocated for the linux boot partition on the card end up becoming mmbcblk0p3 instead of mmcblk0p2?

Re: Repartitioning 16GB SDHC back to FAT
 

I have no idea :\.

But if you check Milhouses's thread, I answered your question of booting of it.