Prerequisites for System Drive too low

[LucaBoschetto]

Describe the improvement you'd like
Update the System Drive size requirements in prerequisites.rst

Additional context
The prerequisites at prerequisites.rst state that the System Drive should be min. 4 GiB capacity. With this capacity, on a fresh install, when I run the first update, the system runs out of space while installing linux-image-6.1.0-0.deb11.13-amd64 6.1.55-1~bpo11+1:

Unpacking linux-image-6.1.0-0.deb11.13-amd64 (6.1.55-1~bpo11+1) ...
dpkg: error processing archive /var/cache/apt/archives/linux-image-6.1.0-0.deb11.13-amd64_6.1.55-1~bpo11+1_amd64.deb (--unpack):
 cannot copy extracted data for './lib/modules/6.1.0-0.deb11.13-amd64/kernel/net/smc/smc.ko' to '/lib/modules/6.1.0-0.deb11.13-amd64/kernel/net/smc/smc.ko.dpkg-new': failed to write (No space left on device)

[ryecoaaron]

How much ram does your system have? The docs say the drive should be "but more than the capacity of the RAM". 4GB is possible but not if your system has a lot of ram because the installer will create a larger swap space for larger amounts of ram. I have a fresh install that only uses 1.7G of space and I had no problem installing updates.

[LucaBoschetto]

I read that specification in the docs, and I indeed set up 1 GB of RAM and 4 GB of System Drive, which according to the docs should be the absolute minimum. Still, that is the error that came out upon upgrade.

Did you do it recently? As you can see, the upgrade that makes it fail is the new kernel.

[ryecoaaron]

My install is from December. I even reverted to snap and install two months of updates. I might not have install with the OMV iso (don't remember). I have a running cm3588 install that is only using 2.9G. Maybe it is harder to keep it small with amd64. I guess I use 16G or larger when creating VMs just to be safe. Maybe the minimum could stay 4G but a "recommended" could be added.

[LucaBoschetto]

I would suggest saying that 4 GB are sufficient for running OMV, but that in case of large upgrades (such as this one) that could not be enough. But still, what's the largest upgrade that could ever be distributed?

[ryecoaaron]

Hard to say. It could conceivably be almost every package on the system the way some OMV users skip updates for a year or more.

[votdev]

I started with a 4GiB DOM, but now i'm on 16GiB. 4GiB can be OK, but only when no additional plugins are installed.

@lucabosc What is your recommendation? How much disk space should be the minimum?

[LucaBoschetto]

Hi @votdev. In my case, 4GB were not sufficient to run an upgrade which included a new kernel on a fresh install with no plugins.

Clearly, how much it would be appropriate to increase the minimum depends on how large future upgrades will be, which we cannot know for sure.

Given that a recent kernel, once installed, can take at most 0.5 GB, plus the compressed space of the package itself, most likely 1-2 GB more should be enough.

In my case, I extended the root partition from 4 to 8 GB and everything went fine.

[PrplHaz4]

I agree the recs are unclear and stumbled on it a bit (and resized multiple times) - maybe say something like (or provide "minimum" and "recommended" separately):

8gb + 1GB for every GB of RAM

Things that will consume disk space that will factor in:

• log files
• installing plugins
• installing docker (even if mounted volumes are elsewhere)
• keeping multiple (backup) kernels - at least 1 version prior should be considered required IME
• recovery tools (via omv-extras)