Keep your roms on and play from network share.
I didn’t see this any where in the forums and thought it may be useful to any one who has more roms than space on their SD card.
This is how i have mine set up, and it works well havent noticed any major issues. I am using a raspberry PI II and running psx isos through the share.
1.) Create a windows share/Samba share on a computer/server in your house preferably hard wired. My share requires a username and password, you may skip step 3 if yours setup does not use them.
2.) make a folder in your home dir
3.) create the .smbcredentials file and set username and password
press ctrl+x, Y, and enter
chmod 600 ~/.smbcredentials
4.) We now need to Edit the fstab so are PI will mount this share on boot. We need this to point to your server you can use the IP of your server or its Host name depending on your set up.
sudo nano /etc/fstab
past and edit
//YOUR-SMB-Server/Path/To/Share /home/pi/games cifs credentials=/home/pi/.smbcredentials,iocharset=utf8,sec=ntlm 0 0
Press ctrl+x, Y, and enter
If your share has no username and password then use this fstab entry.
//YOUR-SMB-Server/Path/To/Share /home/pi/games cifs guest,uid=1000,iocharset=utf8 0 0
5.) To test that are share is working without rebooting we will now run a couple commands.
sudo mount -a
ls -al ~/games
If all went well you should see the files & folders listed on your smb share.
6.)Now for the last bit, run these commands to make a copy of your es_systems.cfg and edit to tune it to your setup. (Updated 3/31/2016)
sudo cp /etc/emulationstation/es_systems.cfg /home/pi/.emulationstation/es_systems.cfg
Find the emulator that you want to use your new network share of infinite storage.
I like to just comment out the path from the default set up like this.
<!-- <path>~/RetroPie/roms/psx</path> --> <path>~/games/psx</path>
Repeat for all emulators you are going to use with the network share.
Press ctrl+x, Y, enter.
You now can reboot your PI and verify that your roms show up and work.