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Ask HN: Ever worked with a service that can never be restarted?

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Re: Ask HN: Ever worked with a service that can never be restarted?

#21

Post by pjc50 »

dijit wrote: post #7

Actually, I have experience here. The problem is that anything you do that's potentially destructive in service of getting the system to be more sustainable is going to be met with heavy criticism. So you must be careful, the company has accepted the risk that they're in and you'll have to contend with that most likely. First thing is first: is it a VM or a Physical machine? Things get a little easier if it's a VM be…

Attaching a debugger potentially disrupts the service. I would suggest trying to live-image it with some other technique first.

Re: Ask HN: Ever worked with a service that can never be restarted?

#22

Post by barry-cotter »

jomkr wrote: post #9

I'm not sure that 55 months of up-time indicates it's more or less likely to go down in the next month, but I'd guess more likely. Surely there are options, have you tried de-compiling the source from the binary? >but the physical config was accidentally overwritten and there are no backups Any old dev PCs lying around somewhere? It's worth reaching out to the old developers to see if they have a copy, in really old…

> I'm not sure that 55 months of up-time indicates it's more or less likely to go down in the next month, but I'd guess more likely.

Less likely

https://en.wikipedia.org/wiki/Lindy_Effect

> The Lindy effect is a theory that the future life expectancy of some non-perishable things like a technology or an idea is proportional to their current age, so that every additional period of survival implies a longer remaining life expectancy. Where the Lindy effect applies, mortality rate decreases with time. In contrast, living creatures and mechanical things follow a bathtub curve where, after "childhood", the mortality rate increases with time. Because life expectancy is probabilistically derived, a thing may become extinct before its "expected" survival. In other words, one needs to gauge both the age and "health" of the thing to determine continued survival.

Re: Ask HN: Ever worked with a service that can never be restarted?

#23

Post by zaphirplane »

You know how with flu vaccine 1 in a big number get sick and with this it may end up worse.

If it’s vm take a snapshot periodically, I suspect it’s not.

Try a p2v which converts it to a vm on the fly, and leave the vm off and periodically rerun the p2v

Re: Ask HN: Ever worked with a service that can never be restarted?

#24

Post by Etheryte »

aequitas wrote: post #13

At a previous job I once sshd into a legacy system which had a motd in the vein of: "Don't ever reboot this system, if you do, I will find you and do horrible things to you". No explaination of why. My opinion was that the person who dared to leave a system in this state was the one who needed the horrible things done to them instead. Needless to say, he was already fired. We started working on solution to run parall…

Shadow traffic is a really good solution here. Aside from simply speccing the system, you're also building a very good automated test suite to run your new solution against.

Re: Ask HN: Ever worked with a service that can never be restarted?

#25

Post by adrianmsmith »

Tilian wrote: post #4

The configuration still exists in memory somewhere, so you could extract it from a dump... whether you should want to do this is an entirely different question though.

That's not necessarily true I think. The program could read the config at startup, and create structures or objects inside its heap to represent the config. After that it would have no need for the actual bytes of the config.

Re: Ask HN: Ever worked with a service that can never be restarted?

#27

Post by arethuza »

scandox wrote: post #14
dijit wrote: post #7

Actually, I have experience here. The problem is that anything you do that's potentially destructive in service of getting the system to be more sustainable is going to be met with heavy criticism. So you must be careful, the company has accepted the risk that they're in and you'll have to contend with that most likely. First thing is first: is it a VM or a Physical machine? Things get a little easier if it's a VM be…

> because the one thing that I learn as I learn more about computers is that they're basically working "by accident" So true. Thanks this is good advice. As it happens it is a physical server. I'm not actually mandated to do anything except replace it with a comparable service but this makes me feel like I'm racing against time!

Have you tried decompiling the executable to see if any sensible information can be gained that way?

Re: Ask HN: Ever worked with a service that can never be restarted?

#28

Post by jwr »

dijit wrote: post #8
blackrock wrote: post #6

Earlier quoted context omitted.

Are you saying there is a device to splice the power cable while it is still hot, and re-route power to the computer without causing a hiccup?

Oh for sure this is possible: https://www.youtube.com/watch?v=vQ5MA685ApE the devices that do it without doing what these guys did is quite pricey though https://www.cru-inc.com/products/wiebetech/hotplug_field_kit...

> the devices that do it without doing what these guys did is quite pricey though https://www.cru-inc.com/products/wiebetech/hotplug_field_kit....

It's somewhat interesting how this company can sell a product which obviously violates pretty much any electrical safety regulations (a plug with exposed prongs that can become hot). I'm guessing this is sold as a kit, not as a complete product.

Re: Ask HN: Ever worked with a service that can never be restarted?

#29

Post by goatinaboat »

capture packet's and see what kind of traffic it receives most commonly

The modern solution would be to capture the incoming packets as a training set then apply machine learning to create a model that can perfectly recreate the outgoing packets.

It’s still an inexplicable black box of course, that is the nature of ML, but at least you can run it in the cloud now.

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