[pve-devel] [PATCH pve-installer v2 3/6] close #5887: add sanity check for LVM swapsize and maxroot

[Michael Köppl]

On 5/6/25 13:48, Christoph Heiss wrote:
> After testing this change and thinking about the maxroot change again,
> $hdsize / 4 doesn't really make sense. E.g. for an (unrealistically
> small, but still) disk of 8 GiB; if its unset, pve-root will be ~6.5 GiB
> in size, with the limit of 2 GiB, the installation fails due to
> ENOSPACE.
> 
> The default calculations try really hard to make installations possible
> even on small disks, in Proxmox/Install.pm:create_lvm_volumes()
> 
> So I'm not sure if we really should restrict it that much, or rather
> relax it in the documentation.

Thought a bit about this. I agree that the sanity check should not
entirely stop users from creating setups that would work. An alternative
approach might be not to enforce the maxroot limit of $hdsize / 4 for
smaller disks. create_lvm_volumes() considers 12 GiB to be small, if I'm
not mistaken, and basically does a best-effort install. I'm not sure if
I like setting such an arbitrary limit for a sanity check, though. It
makes the sanity check intransparent if users cannot configure a root
volume size greater than 4 GiB if their hdsize is 16 GiB, but at the
same time are free to set it to 6 GiB if the hdsize is 8 GiB. What do
you think?

Another alternative might be to simply display a warning that doesn't
stop users from installing, i.e. "Recommended maximum root volume size
is hdsize / 4".

In both cases the documentation should be updated to reflect that.