Those are good questions, and I don't know the answers.
Is the primary partition EXT4? Or FAT or NTFS?
If Ext4, then you could use the other partition as swap.
However, after these couple of issues are resolved, it will take a little research to find out how to properly mount, and have OpenWrt use the swap space.
After the USB HD is mounted and using swap, like it is supposed to, the next step would be installing MiniDLNA. It's a package that is installed on OpenWrt, and I belive can be configured to point clients to the USB HD.
One step at a time -- Figure out how to configure a swap partition on the HD, and mount it. Then configure OpenWrt to use the swap during data transfers.
root@OpenWrt:/mnt/usb# df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 2.8M 2.8M 0 100% /rom
tmpfs 124.5M 88.0K 124.4M 0% /tmp
/dev/ubi0_1 26.1M 588.0K 24.2M 2% /overlay
overlayfs:/overlay 26.1M 588.0K 24.2M 2% /
ubi1:syscfg 30.8M 52.0K 29.1M 0% /tmp/syscfg
tmpfs 512.0K 0 512.0K 0% /dev
/dev/sda 14.6G 38.2M 13.8G 0% /mnt/usb <<<<<<<< Mounted 14Gig USB
(Last edited by davidc502 on 17 Jan 2016, 21:57)