Written 26 Aug 2026. This is a how-to, not a product card. Buy links are not tagged yet.

Check that the leftover-box backup actually copied

After the copy finishes, look on the USB disk and confirm the files are there before you trust it. You do not need a NAS for this look.

A backup is a second copy. rsync is the copy command from a backup of the leftover-box folder. A green terminal without a look is how people learn the USB was empty. This note is the look.

Skip until one backup ran

If you never copied the house folder, do that first: a backup of the leftover-box folder. This note assumes that rsync already finished once.

What this is

You are not buying a NAS. You are asking whether the second copy has files, the same way see if the leftover box still has room asks whether the leftover disk has room. Look on the USB (or the second leftover box) before you trust the copy.

Keep the USB mounted for this look

If you already unmounted after first-backup, plug the disk back in and mount the same way that note taught:

sudo mkdir -p /mnt/backup && sudo mount /dev/sdb1 /mnt/backup

Swap /dev/sdb1 for the partition first-backup used if yours differed. Leave it mounted until you finish this look. If your second copy was another leftover computer over SSH, skip the USB mount and look on that other box instead.

Look at the copy

List what landed:

ls /mnt/backup

You should see a share folder (or the same names you copied). Then compare sizes:

sudo du -sh /mnt/backup

sudo du -sh /srv/share

Those two numbers should be in the same ballpark. Empty or tiny on the USB means the copy did not land. If you copied to another leftover box, list and size that share folder there the same way.

Spot-check one file

Open a photo or a document from the USB on the leftover box, or plug the USB into your laptop and open one file there. Do not trust the terminal alone. One real file you recognize beats a green prompt.

Then unmount

When the look is done:

sudo umount /mnt/backup

Unmount before you yank the cable. Leave the disk unplugged most of the time, same advice as a backup of the leftover-box folder.

If the copy is empty or tiny

Re-run the rsync from a backup of the leftover-box folder. Check the USB is writable and not full:

df -h /mnt/backup

Disk room on the leftover box itself is see if the leftover box still has room. Do not buy a NAS for a failed first copy.

What next

After one real copy works, back up the leftover-box folder every week without remembering. Wrong clock: set the leftover box clock to your house. Skip RAID. Skip restic and Borg. Skip cloud until the USB copy exists.

Skip

• Skip if you never ran a backup of the leftover-box folder.
• Skip a NAS for this look.
• Skip RAID.
• Skip leaving the USB plugged in forever.
• Skip the 3-2-1 lecture tonight.