is ext2 or 3 the only choice for SD card?

[macwiz]

I'd like to install things to my 64MB SD card, but I understand that FAT is just no good for installing applications on with the pdaXrom. Unfortunately my SD card is a SanDisk that works well as FAT but is hopeless when formatted ext2 or ext3. Are there any other formats I could try that it might behave better with and that I could install applications on?

[macwiz]

Err, I take it that's a 'no' then.

Ah well.

Still, for any one who hasn't got money to burn on hi-capacity SD cards that might not work, it cheered me up no end when I stumbled upon the installer options for the pdaXrom that allow you to make the root partition 121 mb instead of 50 mb. Brilliant work! Now I can put my apps on the internal drive, and use the SD for storage (because it works fine when formatted FAT). Still like to know if there are any alternatives that will work though.

Thanks

[pgas]

I think the main problem with FAT is that you can't make symbolyc link.

Here is a thing you can do, this is a diy solution and requires some hand works :

- install the applications on the internal flash
- move some files (not symbolic links ;-)) to the sd card. (you can use ls -l and symbolic links will be marked with a l at the begining of the line
- use ln -s /mnt/card/myfyle /original/path (you can consider ln -s is working like cp and link entire directory)

This is perhaps not the greatest solution, but this way you can transfer some kb to your sd.

(I still don't understand the problem with the 50mb root partition, except
that you must be a bit more careful, if you have a 50 mb partition, just install to /home/user or /mnt/user and apps will go in the other partition

[macwiz]

I guess I might appreciate the other places to install apps more if I knew how much space I had on them. Is there an equivalent to diskfree? Or a command that returns free space values?

[blakeyez]

Is there an equivalent to diskfree?

Code: [Select]

df -h
should do the trick.

Dave

[offroadgeek]

Unfortunately my SD card is a SanDisk that works well as FAT but is hopeless when formatted ext2 or ext3.

that's odd... I have several sandisk SD cards, and I keep my 256mb Sandisk SD card always in my pdaxrom 760 formatted as ext3... with no issues.

what specific errors/issues do you get when formatting your SD cards to ext2/3?

edit:  I take that back... I've actually been using ext2 with my SD cards... but still no problem with that

[rgrep]

You could also try UMSDOS.  I'm not sure if pdaXrom supports it but it allows you to have a Linux filesystem layer on top of a FAT-formatted disk.  It supports everything a standard Linux filesystem does (e.g. long filenames, symbolic links, permissions).

[macwiz]

The SD card I have is a 64MB sandisk. It appears to format fine. I install apps to it, and they appear to install fine. They work for a while. Then all of a sudden they don't. I unmount the card and do an e2fsck, and then one of 2 things happen. Either I am told there is an invalid superblock and I should try an alternate superblock option (which I do and get the same error). Or I can fix the filesystem, but only if I use the -y option, because the fixes scroll up the screen forever. Once it has done its work I mount the SD and still nothing works.

I never get a problem with a fat format.

Will look into the UMSDOS format. Might be a while though.

Thanks

[richardh]

I am in a similar situation with a 1gb card that works fine as fat32, but am reluctant to format ext2/3 given the issues many have had so I have been using it for bulk storage only. Your post made me start thinking about options and here is what I found works. Use a loopback mount to utilize space on your "safe" fat32 partition as ext2/3

Steps:

1) Create space to be mounted as ext2/3. Example is 100MB where ext2.img is on your SD card
# dd if=/dev/zero of=ext2.img bs=1024 count=102400

2) Format as ext2 (or 3...)
# mkfs.ext2 ext2.img
mke2fs 1.34 (25-Jul-2003)
ext2.img is not a block special device.
Proceed anyway? (y,n) y

3) Create a mount point
mkdir /mount

4) Mount file as filesystem
# mount -o loop,rw -t ext2 ext2.img /mount/

Seems to work fine... no ext2/3 formating risk to your SD card and all of the benefits of a real unix filesystem.

-Richard

[scoutme]

interesting... I'll keep it in the golden hints
going to use it if any prob occurs.

What do you find in the so used fat32 if you navigate it from a windows box?

[richardh]

Just a big file, nothing special about it really.

[henrysviper]

I was thinking about the ext2-in-a-file solution too, but I was curious about the performance penalty due to this indirection. Richardh, could you please perform some simple benchmarking for us? (Thank you for the detailed instructions by the way).

[kopsis]

I'm loop mounting an ext2 filesystem image for running Python from an SD card and I really don't notice any performance degradation from the loop overhead. SD card bandwidth on the Zaurus is the bottleneck so adding a little CPU overhead for the indirection really doesn't hurt anything.

[anunakin]

ext 3 need more CPU calls, for a bit of util thinks for a PDA... use ext2... is the better choice for SD/CF...

[Zumi]

ext 3 need more CPU calls, for a bit of util thinks for a PDA... use ext2... is the better choice for SD/CF...

But pdaXrom likes to freeze sometimes and then you have to fsck the whole ext2 partition, maybe you lose files, partiton integrity. Ext3 restortes the state before-freeze in 1 sec while booting.

So I think ext3 is far better, but not for performance reasons. I haven't done any performance test with them however, so I don't know what is the speed difference.

Zumi