2017-06-28

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What is this "backing_file" on my NAS?

Huh. I was creating a new shared folder on my NAS through its web interface, clicked on the wrong thing, and discovered its drive is pretty close to full.

Well, I figure I've been putting a lot of backups on it. Maybe the pruner for that or the log rotater isn't doing what it should? But no, those are fine.

Then, poking around, I accidentally discovered that in the shared folders directory (/mnt/disk/volume1), there's a file called "backing_file", which is 400G. It's binary, and hasn't been updated since Apr 17 2013.

WTH?

I'm trying to decide if I can delete it or not. It's not impossible I created it by mistake, back when I was setting up my backup system, but I don't know how. Google's only apparent association with that string and Debian is for a utility, qemu-img, which I'd never heard of. I've not messed around with disk images in years and years, and never on that device.