You wouldn't want to power directly from the panels without a battery. It would cause high instability on cloudy days, possibly leading to file system corruption.
The panel voltage is pretty stable until the illuminance gets really low (unless you're drawing a lot of current). Diodes such as solar cells are roughly constant-voltage devices. You can get a pretty long way avoiding filesystem corruption by mounting things read-only, but (I've heard) some SSDs aren't really read-only even when they're read-only, because of read disturb and the attempt to compensate for it in the FTL. 10 seconds of 2 W at 3–6 V is about two farads, so you might be able to get acceptable stability with a supercapacitor in the 1–10 farad range instead of a battery.
"The panel voltage is pretty stable until the illuminance gets really low"
I'd like to see what panels those are, because the ones I've built while working as a PV manufacturing tech, both mono and poly (roughly 21% efficiency,) will have greatly varying voltages with even the tiniest hint of cloud cover over one cell, even with the junction box working to help separate out sections of the panel to maintain better voltages. Typical 60 cell 30-32V panel will drop to ~18-20 with just two cells on one 20-cell section of the panel covered. Sure this is still enough for the paltry voltage this specific server needs, but if they used smaller and more affordable panels like those used for cell phone chargers or similar size (within about 18"x18" form factor,) I can guarantee you those do not take to shading or even bad orientation well at all. 45 degrees off direct-exposure and you could be looking at that smaller panel producing a mere 2V or less.
Is that the MPPT voltage or the open-circuit voltage? I was thinking of a near-open-circuit voltage (which is what you have if you're powering a 2-watt webserver from a 50-watt solar panel), but MPPT will vary a lot more. Also, covering 6% of your cells will drop your voltage a lot more than covering all your cells 6%.
Open circuit. This is one specific behavior we looked out for when testing panels before shipping, after the EL test, lamination, and junction box installation.
With DNS failover there is only added latency during the time interval between when a server goes down, causing the DNS to get updated, and when the dead IP times out everywhere, which can easily be a few minutes. If the server can anticipate that it is going to go down it can remove itself, and then only people using shitty ISPs that don't respect the TTL will ever see extra latency.
> and then only people using shitty ISPs that don't respect the TTL will ever see extra latency.
In my experience running large websites, that's about 10% of the internet, if not more.
When I made a DNS change, only about 70% of the traffic dropped off in the TTL. The rest took anywhere between a few hours and a few weeks (and some never dropped off, we had to just let them fail after a while).
I don't think so. DoH deals more with streamlining the transmission of requests and responses, but I don't recall any part of the RFC dealing with TTLs.
You'll still be talking to your local DNS server with its own caching rules.
I thought part of the big deal with DoH was precisely that you don't use your local DNS server (or more importantly, your ISP's DNS server). If DoH effectively means that more people pull DNS straight from Cloudflare, then I would expect the TTL situation to improve.