... if you're going to backdoor a product, may as well be as close to the requester as possible.

Did they check for an underground car park next door?

Apparently the underground carpark is above it!

[1]Quote : "Constructed by Bynet Data Communications, the underground facility is a 14,000 sqm (460,000 sq ft) bunker locate below five parking levels and a 17-story building in Jerusalem’s Har Hotzvim tech hub. The data center extends over four floors at a depth of 50 meters (160 feet) below ground level."

[1] https://www.datacenterdynamics.com/en/news/oracle-opens-israeli-cloud-region-underground-jerusalem-data-center/

Tempting fate there.

And, besides, are they entirely certain? If there are on site generators, they'll have exhausts no? What happens if one drops something that goes bang down there?

Don't be silly, nobody needs to worry about a small thermal exhaust port..

Rocket? I've seen Beverly Hills Cop, all you need is a banana up the tailpipe of the generator.

Exactly, reading that comment, I can imagine some idiot saying "Challenge accepted" and doing something just to proof a point.

But can the *fibre* connecting it withstand the above?

Flatbed trailer, 60 metric tons of ANFO, ground zero "close enough". Though the servers will continue to run, they will be as good as dead to the rest of the world. A few hours of being considered destroyed and the HA state will obsolete most of what they still keep.

As for archives, I would not put my archive in a place which just tempeted fate this boldly.

What about flooding at that depth - I suppose they could say it's water-cooling

Depends where the groundwater is. 50m is probably below groundwater level, but not necessarily (though the article refers to Jerusalem, so I suspect quite shallow groundwater there)

Also, depends on what the soil/rock is - is it low permeability material? If the surrounding soil/rock is sufficiently low, you might have nothing more than a little dampness to deal with, as the inflow evaporates as quickly as water passes through the soil. On the other hand, if you are in sands and gravels, you are effectively in a lake.

Then your waterproofing strategy come in.(various ways of waterproofing a basement, giving varying effectiveness based on intended use). You might aim to build a 'water proof' (very low permeability) structure to keep all the water out, or have an internal liner wall with a drained (and pumped) cavity between inner and outer walls.

So, good question (have an upvote), but also a typical issue for the construction industry to deal with.

IRTA as Nine Feet Underground, is 70s band Caravan back in fashion?

Surely the size of the missile determines if its reachable or not ?

There is also the option of using more than one missile too :-)

MOAB is effective through 200ft of reinforced concrete.

But fortunately jihadi scumbags don't have any MOAB's.

The ability of an explosive projectile to damage the data centre will depend on (amongst other things) how deep the projectile penetrates before going bang, and how big the bang is.

How deep the projectile penetrates (You at the back of the room, stop sniggering...) depends on the nature of the soil, or rock, or other cover (e.g. reinforced concrete slabs), shape of projectile, and impact energy (roughly linked to drop height if it's a bomb).

The effectiveness of the projectile (whether the bang damages the buried structure) then depends on the power and nature of the shock wave formed when the projectile explodes, and nature and thickness of intervening soil et al (dissimilar layers appear to be beneficial in retarding the shock wave, for example).. Also, the nature/strength of the structure, of course.

As a very rough guide, WW2 unexploded bombs are generally felt to reach a maximum bomb penetration depth of up to ~21m, though most are found at much shallower depths (typically <10m depth).

The threat here is presumably the sort of truck-mounted multi-rockets ('Katyushas') used by Hamas et al. These seem generally to have quite limited penetration ability, and, in the grand scheme of things, don't go bang particularly loudly. Multiple missiles would just pound the surface to dust, and then recirculate the dust on the surface.

On the other hand, the left-pondian air force is currently testing an air-dropped 5000lbs bunker buster: that would I suspect lead to a loss of service at the data centre..

Less of a worry about disruption in Israel than in France. If Oracle don't give the French preferential treatment, they'll pull the plug and blockade the entrances.