Internal SD-card hardware erros. Is there a way to move partitions to external sdcard? I have a device with hardware errors in the internal sd card and want to move /data entirely to the external sd card.
I was thinking that it should be possible to create a partition in external sd-card and use it instead of the default partition for /data/ so that only system partition (which is read only ) will remain on the internal SD-card and this will reduce the chance of errors.

How can I change the initial mount options to make android mount /data from external SD card. ? 

EDIT:
One solution is fstab modification,In Linux PC it's quite simple,  modifying /etc/fstab. will it work on the equivalent fstab for android ?
On Android it's not that easy to modify the "fstab", as that's often stored inside the boot-image (see Wikipedia on "initrd" for a more detailed explanation).

However, depending on the device, there might be alternative solutions. Some of them would be:


DirectoryBind binds "directories located on external_sd to directories on internal memory (/sdcard). This way You can transfer large application data directories to external_sd." (in other words, you could compare that with "symbolic links", pointing to the external SDCard). See also this article.
Swap Internal and External sdcard. According to the linked article, this should work for ANY Android Phone or Tablet. This solution is comparable to your "editing of fstab".
Root External 2 Internal SD is an app to swap the cards. From its description, it does the same as described in the previous point.


There might be more solutions around, but these are the ones I've heard of. Hope one of them can help you out!