Update uses less space?

[matthew.j.hill]

Okay--now this is a weird one, and I couldn't find anything about it online.  It's more of a curiosity than an issue, but I would like to understand what's going on.

I created a new OPNsense firewall, using a freshly-downloaded OPNsense-21.1-OpenSSL-dvd-amd64.iso image.  Following the guidelines here: https://docs.opnsense.org/manual/hardware.html I gave it a 40 GB root disk for a "reasonable" install.

I was a little surprised that it only ended up taking 2.1 GB after install.  I'm not quite sure why the hardware guide recommends so much storage.  In fact, the "recommended" size is 120GB, which would've been <2% used.

But that's not my main question.  After installing, I immediately updated from the System->Firmware->Updates page, and that brought me to 21.1.5.  To my surprise, disk usage dropped by a full 300 MB, down to 1.8 GB.  I can't remember seeing a software update take up less space than it's predecessor--and certainly never by a full 15%.

I did install a whole slew of plugins, and that brought me back to 1.9 GB used.  With everything configured and running fine for a while now, it doesn't seem to be growing much.  But I'm wondering, did the fresh DVD install just come with 300 MB of cruft that the update cleared out?  I have no idea what files went into the chipper as I didn't do a before/after comparison.

[marcquark]

The recommendations make sure you'll never have to worry about storage. Depending on what you do, disk space consumption may go up, but typically never get close to filling your disk completely, and that is good.



Regarding the update reducing disk usage: Possibly some old dependencies went out the window due to optimizations

A clean install will use very little disk space. However when you turn up your logs and keep them for at least a few days, or when you configure the web proxy for caching, then you'll quickly see more disk space consumed. Granted, the recommendations are high compared to how little OPNsense usually consumes. It always depends on how big your environment is though.
But i would really look at it this way: The recommended requirements are moderate/low compared to what you see with other security products and appliances. In practice, you usually barely go beyond 15-20% usage, even with many of the features enabled. So, the software is just pretty damn efficient, and there's plenty of room to grow and you'll never have to worry about disk usage. It's also the last thing you want to worry about on a network appliance. A 120 GB SSD is like 20 bucks or even less nowadays, not really a big deal imho

Also having a lot of free space on an SSD will increase its lifetime, so there's another plus

[matthew.j.hill]

Yeah, disk space is pretty cheap these days.  I "grew up" in computing when that was not the case, however--and I guess it's still a little hard for me to look at a disk that has 6% utilization.

OPNsense is running on a slice of a bigger disk that's also used for other things, so I could have used some of the space for something else.  Or I can just add another disk.  Strange that we live in a world of $20 SSDs and video cards & CPUs you can't even buy at $1000.

That makes sense about the dependencies.  I didn't think about that.  Usually it's bloat that gets added in updates, not dependencies removed.  Good that the developers are keeping up on housekeeping like that.

[danielm]

Anything less than 120GB or so has terrible IOPS and longevity so I would avoid it. Also smaller SSDs are not much cheaper because nobody buys them.
The disk util will go up a little with logs growing and package caches filling up. Also there should always be a few gigabytes of free space for installing of upgrades.
Additionally, some plugins will lead to a much higher disk util, e.g. ntop