Title text: Asimov's Cosmic AC was created by linking all datacenters through hyperspace, which explains a lot. It didn't reverse entropy--it just discarded the universe when it reached end-of-life and ordered a new one.
|| This explanation may be incomplete or incorrect: No details|
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RAID ("redundant array of independent disks") is a technology that splits data across several hard-drives as if they were one. RAID comes in several levels for different uses, but one of the big applications of RAID is creating mirrored hard disks that back each other up. If one disk drive in a RAID array fails, no data is lost.
However, RAID is complicated to configure, so you don't want to be constantly setting it up. An alternative technique for data centers is therefore to simply send the data to several servers at once. This makes maintenance easier, but without RAID, one hard disk crash basically breaks the server.
From here, the comic starts to exaggerate. Nowadays, servers can be made extremely small ("Blade servers") and dozens of servers can be attached to one 19-inch rack in a data center. Rather than going to the effort of unplugging and unscrewing one blade from the rack, when a blade fails at Cueball's data center they just throw away the rack.
Hairy's goes one step further - they have so many servers that they would constantly have to be throwing away and replacing racks, so instead they just build a new room when one rack fails. This would be currently possible with small modular data centers that are built in shipping containers for easy transport and can be linked together to expand capacity. Here the cargo-container "room" with the failure would be quickly swapped with a fresh one. Cueball adds "like Google!" - Randall previously mentioned Google's approach to hard drive failures (back in 2007 they had one failure every few minutes - that might have increased hugely since then) in What if? 63 - Google's Datacenters on Punch Cards.
Finally Megan appears, and says that they don't have any fire extinguishers (inert gas systems flood the room with gases like argon which force out oxygen and stop fires - these are better for computers than traditional water or powder systems). Rather, they just let the data center burn down and build a new one. Most big internet companies do have multiple redundant data centers around the world, in order to increase speeds for users in different countries, but Megan's idea would be very expensive, increase in latency and also kill people.
This comic references how, as data requirements expand, companies rarely use more specific, but time costly choices when working with data centers, and use more expensive but faster solutions. While this comic takes this to the extreme, with whole buildings being destroyed for simple flaws, the concept is not as far fetched as it seems if "thrown out" is taken to include being sold to equipment refurbishers. It could indeed be cost effective for a large data services provider to resell racks or even whole data center modules at some significant fraction of their "as new" price as opposed expending the time and effort to attempt a repair. The equipment refurbisher would then rely on a cost advantage like cheaper labour to repair the flaw and sell it back to Google or another company with less demanding requirements. Equipment rental firms already operate on this model and with the added incentive customers preferring to rent newer models, this means that the equipment is often preemptively replaced before failures even occur.
The title text refers to Isaac Asimov's science-fiction novella "The Last Question", where humanity asks, at differents stages of its spatial and technological development, the same question to increasingly advanced computers: "How can the net amount of entropy of the universe be massively decreased?". At each point, the computer's answer is that it doesn't have enough data for a meaningful answer. Ultimately, the computers are all linked through hyperspace, outside the physical boundaries of the universe, and make up a single computing entity named AC which keeps pondering the question even as the heat death of the universe occurs and time and space cease to exist. When AC finally discovers the answer, since there is nobody left to report it to, it decides to demonstrate it and says "LET THERE BE LIGHT!", which are the first words said by God during the Creation, according to the Book of Genesis. Here, the title text implies that, as the universe died, AC no longer had a use for it as a physical support and, taking the comic's logic to the next extreme, chose to discard it and order a brand-new one instead of bothering to "fix" it by reversing its entropy.
|| This transcript is incomplete. Please help editing it! Thanks.
- Hairbun: RAID controllers don't make sense at our scale; everything is redundant at higher levels. When a drive fails, we just throw away the whole machine.
- Cueball: Machine? We throw away whole racks at a time.
- Ponytail: Yeah, who replaces one server?
- Hairy: We just replace whole rooms at once. At our scale, messing with racks isn't economical.
- Hairbun: Wow.
- Cueball: Like Google!
- Megan: We don't have sprinklers or inert gas systems. When a datacentre catches fire, we just rope it off and rebuild one town over.
- Hairy: Makes sense.
- Cueball: I wonder if the rope is really necessary.
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While the comic is obviously exaggerating, there are situations where this could make a certain amount of sense. IF you can design a server so that most or all of the components reach end-of-life at about the same time, then if a hard drive fails on one server, every other component of that server is likely to fail soon as well.
If you install entire server racks or server rooms at the same time, where every machine contains components with the same basic life cycle...
then in theory, once the first component fails, you can ignore it until mass component failures causes the entire rack/room to fall below a certain readiness level.
At that point, there's no reason to pay a technician to spend several days removing and replacing half the individual components throughout that rack/room, when the other half are just going to fail in the next few months anyway. In theory, it might be economically more efficient just to scrap everything at once, bring in brand-new server replacements, and re-sync the needed data from a networked backup.
in real life, it's very hard to build a server that will reliably degrade on schedule.... but with the right tradeoffs, and enough long-term performance data, it might eventually become possible to do so.
126.96.36.199 04:48, 23 September 2016 (UTC)
- Or give the equipment to someone with a different time/ROI equation. I've seen a lot of time/expense burned on a transient failure that turned out to be a cheap data cable. A kid/disadvantaged would have time to tinker this out with a potentially significant payoff. Elvenivle (talk) 17:27, 23 September 2016 (UTC)
The title text is referring to The Last Question by Isaac Asimov.
EpicWolverine (talk) 04:56, 23 September 2016 (UTC)
I cannot help but read this in a fake Yorkshire accent. https://en.wikipedia.org/wiki/Four_Yorkshiremen_sketch 188.8.131.52 09:55, 23 September 2016 (UTC)
I wonder how closely the AC and Douglas Adams' Deep Thought are related? 184.108.40.206 (talk) (please sign your comments with ~~~~)
- Not that close as Deep Thought was build inside this universe and also finished it's job and was recommissioned. They build a new computer (Earth) instead to calculate what the ultimate question was, now they knew the answer was 42. But maybe Adams was aware of AC and based the idea of solving a question with computers on that...? --Kynde (talk) 13:56, 23 September 2016 (UTC)
I think the character in Panel 1 is Science Girl and not Hairbun.
PoconoChuck (talk) 12:20, 23 September 2016 (UTC)
- Agree it fits with her style and she has appeared as an adult before. She also seems smaller than the other people so it could indicate she is still young. I created the Science Girl and the Hairbun categories, so I should know ;-) When a character fail I just throw it out and create a new one... :p --Kynde (talk) 13:52, 23 September 2016 (UTC)
- It's clearly not Science Girl, because, as the linked page says "She became the first child to have its own character category. She is distinguished by being clearly a girl (compared to adults around her or her behavior)". You may create a page called "Datacenter Woman". 220.127.116.11 14:35, 23 September 2016 (UTC)
- I dunno - she's drawn exactly like Science Girl - right down to the frizzy hair below the bun that's never been seen on Hairbun (who doesn't have black hair either). There are plenty of other instances of "child" characters being seen as young adults - and of people acting out of character when "bit parts" are needed in cartoons. The resemblance is too close to be a coincidence. SteveBaker (talk) 20:41, 23 September 2016 (UTC)
- No need to invoke blade servers
There's no need to refer to blade servers in the explanation. You can fit many "normal" servers into a 19 inch rack. It could just say:
- From here, the comic starts to exaggerate. Many servers can be mounted in one 19-inch rack in a data center. Rather than going to the effort of unplugging and unscrewing one server from the rack, when a disk fails at Cueball's data center they just throw away the rack, and Ponytail agrees and kinda mock the woman with a bun for replacing a single server.
18.104.22.168 14:51, 23 September 2016 (UTC)
- RAID is not complicated
Simple RAID 1 is not complicated to configure, unless you have some exotic HW RAID controllers. RAID 5 would be more complicated AND requires to be HW, but RAID 1 will usually be simple as HW OR possible to do SW completely automatically. What is costly is to replace discs as they fail, because it must be done by human ; in bigger systems, it makes more sense to start with RAID 1, then when one disc fail simply ignore it - not repair nor throw it off, just let it operate without the RAID. -- Hkmaly (talk) 15:41, 23 September 2016 (UTC)
- Actually, depending on OS and software other RAID levels can be done in software, too. I've done RAID levels 5 and 6 fully in software using mdraid on Linux. Neither of them are really that much more complicated than RAID-1. ZFS can do even more complicated "RAID" types fully in software, too. Iguanabob (talk) 16:55, 23 September 2016 (UTC)
- Gas-based data center fire extinguishers are not lethal
There's an explanation in this article which claims that gas-based data center fire suppression systems are lethal to anyone in the room when they are deployed. This is a myth, based on some very ancient systems which used halon. For decades now, agents like FM-200 have been used, which alter the air's ability to sustain a fire without removing oxygen from the room. See this video [ https://youtu.be/-ub8gwgcOns ] for an example. The camera crew is IN THE ROOM when the system is deployed. Trust me on this, I've worked in data centers for 20 years and know this stuff inside and out. IGnatius T Foobar (talk) 16:17, 25 September 2016 (UTC)