Written 24 Aug 2026. This is a how-to, not a product card. Buy links are not tagged yet.
A backup of the leftover-box folder
A second copy of the house folder, on a USB disk you already have, or on another leftover computer. You do not need a NAS for this.
The share on the leftover box is useful the day that box dies, only if a second copy exists. That second copy is a backup. Same leftover box. Same SSH from the couch.
What this is
A program called rsync. A tool already on Debian and Ubuntu that copies a folder and, next time, only copies what changed. You do not buy Synology Backup or a cloud plan for a folder of photos.
This assumes the share from a file share on the leftover box, or any folder you care about, like /srv/share. Debian or Ubuntu Server, the OS from what OS to put on the leftover box, installed as in your first weekend. SSH in from the couch.
What we would do
| Where the copy lives | When to pick it |
|---|---|
| A USB disk you already have | The default. Plug it in, copy, unplug. You do not need a second computer. |
| Another leftover computer on the house network | You already did the first weekend on that box too, so SSH already works. |
USB disk you already have
Plug the disk into the leftover box. Find it with lsblk. That is a list of disks. It often shows up as /dev/sdb1. Use the name lsblk actually printed, not a guess.
lsblk
Mount it, which means make the USB disk show up as a folder:
sudo mkdir -p /mnt/backup && sudo mount /dev/sdb1 /mnt/backup
Then copy the share:
rsync -a /srv/share/ /mnt/backup/share/
The trailing slashes matter. They tell rsync to copy the contents of the share into that backup folder. Leave both slashes on.
Another leftover computer
If you have a second leftover box on the house network, copy the share over SSH:
rsync -a /srv/share/ otheruser@other-address:share/
Swap otheruser and other-address for the login and address of that second box. Trailing slashes still matter, same as the USB copy. That lands in a folder named share in the other user's home.
After the copy
If you used the USB disk, unmount it before you yank the cable:
sudo umount /mnt/backup
Leave the disk unplugged most of the time. A leftover-box problem cannot also wipe a copy that is sitting in a drawer.
Do it again next week
Same command. rsync will skip files that did not change, and copy the ones that did. A reminder on your phone is enough for now. cron, a timer on the leftover box, can wait.
What next
Leave it. Use the folder, and copy it again next week. A VM is this note, still later. Not a NAS. Not RAID. Not Backblaze on day one.
Skip
Skip buying a NAS for backups. The USB disk you already have is enough. Skip RAID. RAID is not a backup. Skip restic and Borg on day one. Skip a cloud plan until the USB copy exists. Skip the 3-2-1 lecture. Skip leaving the USB plugged in forever.
Sources
Debian: rsync man page. Ubuntu: rsync man page. Official pages only. For the share this copies, see a file share on the leftover box. For the leftover box install, see your first weekend. A dedicated file box is later: a first file box (NAS).