mounting multiple usb flash drives

[gorgar19]

this question has nothing to do with the raspberry pi 4 nor when will it be ready but what im trying to do is motivated by the hope that when its all said and done that some games for the 3do system will be playable.

so i decided o do a clean build from a fresh image using the most current image from here for the p3 b+ to try and refresh my memory as as at best i m a read the steps follow steps level of user.

what i wanted was one usb stick to have the roms i currently have on my system and a second with the 3do and dreamcast roms on the second one.

i thought i could get a way with creating a folder /retropie/roms/dreamcast but that just gets the roms moved over to the main usb flashdrive filling the first usb flashdrive
.something i dont want as the 3do roms are fairly large .
then i though maybe deleting the dreamcast folder on the main usb stick would help but that was a nogo as well

so my question is what im trying to do supported or would i have to treat the second usb stick like an external drive and manualy mount it .im assuming i will need to disable usb rom services but that seems counterproductive .

[luizsaluti]

By editing /etc/fstab you could get one Disk to be mounted at an specific directory, like /home/pi/Retropie/roms/3do . When you point to that directoty you will see the root directory of your drive. So your roms would have to be at the there, at the root of your hard drive.

issue the command

sudo apt-get update && sudo apt-get install ntfs-3g;

then

sudo blkid;

All avaiable partitions will be displayed, take note of the UID of the partition you will be using as a rom folder.
Supposing you are using an ntfs file system, add a line to the /etc/fstab file like below:

UUID=YourPartitionUid        /home/pi/Retropie/roms/3do     ntfs-3g   rw,nofail 0 0

You can do the same stuff to other disks you intend to use as rom folders.

[mitu]

The usbromservice will auto-mount over the /home/pi/RetroPie folder, so you can't use something automated and supported OOB right now for both drives.

Since the roms folder read from the 1st disc, you can manually set-up a mountpoint for the 2nd disc and then bind-mount the dreamcast and 3do folders. Something like

# mounted from `/etc/fstab` 
mount  /dev/sdb1 /mount/disk2

# additional bind mounts that can also be added to `/etc/fstab`
mount -obind /mount/disk2/3do /home/pi/RetroPie/roms/3do
mount -obind /mount/disk2/dreamcast /home/pi/RetroPie/roms/dreamcast

[gorgar19]

Thanks you guys are the best

[tpo1990]

As an alternative you could create soft/symbolic links from the roms folder on your two usb drives to the systems roms folder on RetroPie.

The command to do so would be.
ln -s file1 link1

An example of linking psx roms from usb drive to the psx roms folder on RetroPie

ln -s /media/usb/psx /home/pi/RetroPie/roms/psx

This will create a soft symbolic link of all the files in the specific folder.

Look at the file1 as the source and link1 as the destination and change them to the correct location of each folder.

This is what i have done and it works most of the time but sometimes it does not as it looks like the mount of the USB name changes when restarting the RPI and that breaks the soft links. This approach is great if you don't want the usbromservice to move everything and just want to keep only the roms on the USB drive.

Edit: I think that maybe by using both soft symbolic links and then make sure that the USB drive always will be mounted as ex. USB0 or Your USB Drive then it would work great.