In this post, I would like to show how to mount Internal SD card and External SD card when using Cyanogenmod 7 ROM.
I had some issues because CM7 mounts the internal SD card under /mnt/emmc and mounts external SD card under /mnt/sdcard.
As you know, there are many applications that download data using /mnt/sdcard as path and if you have CM7 way of mounting these apps won't work.
So to mount Internal SD card to /mnt/sdcard and External SD card to /mnt/sdcard/external_sd as it is done on Stock ROMs proceed with the following:
1 - Open the file /etc/vold.fstab with your preferred text editor (I use root Explorer) and find and modify the last lines as below an then save:
# internal sdcard
dev_mount emmc /mnt/sdcard 28 /devices/platform/msm_sdcc.1/mmc_host/mmc0/mmc0
# external sdcard
dev_mount sdcard /mnt/sdcard/external_sd auto /devices/platform/msm_sdcc.3/mmc_host/mmc2/mmc2
# otg sdcard
usb_mount sdcard2 /mnt/sdcard/usbStorage auto /devices/platform/msm_hsusb_host.0
2 - Open the file /system/build.prop with your preferred text editor and find and modify the following lines as it is show an then save:
# notify vold we have internal and external sd
3 - Reboot the phone and voilá
This procedure worked for me and I have no issues to mount both my Internal and External SD cards when plugging the phone on my laptop.