Why doesn't OSX crash?

I don't understand why Windows can have blue screens while OSX never crashes. Is it because OSX is more of a closed platform, and thus it just naturally will not, or is there something about the code that literally prevents complete crashing from happening? I searched online and couldn't find an answer as to WHY Macs don't crash, just a bunch of fanboy articles about the fact itself. And remember that I am not talking about application crashes. I am talking about full-fledged crashes like BSODs that force a restart.

There are, primarily, three (er, five, sorry) reasons why a full-blown crash is so rare in OS X:

1. OS X is built on an incredibly robust and reliable UNIX base. UNIX is a very old OS (over 40 years!) and is rock-solid. It was originally designed (and still is) to run for months without rebooting, though a little light maintenance (and keeping lots of temp space clear) will really help it remain robust.

2. Protected memory. Applications are "walled off" from each other, and nowadays even processes are "walled off" from each other, so that if something fails it doesn't take the whole system down with it.

3. No registry. This is the primary reason why OS X is so much more hearty than Windows. A central registry of system functions all interacting with numerous applications (and versions, and functions, etc) was simply a bad idea, but it's too deeply embedded in Windows infrastructure to just take it out. Maybe Windows RT avoids this bad idea, I don't know, I certainly hope so.

4. Security. UNIX and OS X are designed with security in mind, whereas with Windows security was always a bolted-on thing. This means that Windows is far more vulnerable to malware of all types than OS X is, which can add to system instability. Finally:

5. Higher standards. Macs are notoriously pickier about the quality of RAM the machines will work with, which turns out to be really crucial to system stability as, at any given time, a fair amount of the system is loaded into RAM and written back to disk. You want RAM that can do this accurately and reliably. Windows systems, at least the ones I am familiar with, were never so picky and consequently had more errors in that area that can lead to system instability.

And while not nearly so common as in Windows due to the above, there are full blown system crashes in OS X. They are called kernel panics or kp for short. Most of these are indicative of a hardware failure but can be caused by bad software.

In some ways, this is a bit of a myth. OS X can crash and sometimes, it's quite the spectacle. When it does, it's sometimes just as hard to determine the cause as it is with a BSOD. On the other hand, Windows stability has improved dramatically over the years. Unlike versions such as 98 or ME, I've only seen W7 die gloriously a handful of times. That said, on the whole, OS X tends to be more resilient and it manages to handle system errors with a little more grace.

chas_m said:

2. Protected memory. Applications are "walled off" from each other, and nowadays even processes are "walled off" from each other, so that if something fails it doesn't take the whole system down with it.

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Protected memory is not OS X specific. In fact, it's been a part of Windows since NT 3.1.

If you're talking about "walled off" as something analogous to sandboxing (I'm not suggesting that you necessarily are but it comes up a lot in discussions like this), you might want to look up what sandboxing means in this context - it's more about resource access and security, not stability.

chas_m said:

5. Higher standards. Macs are notoriously pickier about the quality of RAM the machines will work with, which turns out to be really crucial to system stability as, at any given time, a fair amount of the system is loaded into RAM and written back to disk. You want RAM that can do this accurately and reliably. Windows systems, at least the ones I am familiar with, were never so picky and consequently had more errors in that area that can lead to system instability.

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That's news to me - I've thrown all types of RAM at a Mac and this has never affected the operation of the machine. Remember, at it's very core, a Mac doesn't have a special motherboard that is somehow unique relative to the rest of the market. It may have back in the day but it doesn't anymore.

Another thing to add is that Apple knows exactly on what hardware their OS will run ( Apple computers ) whilst Microsoft needs to ensure their OS runs on all kinds of different hardware, resulting in all kinds of compatibility requirements.

Cheers ... McBie

McBie said:

Another thing to add is that Apple knows exactly on what hardware their OS will run ( Apple computers ) whilst Microsoft needs to ensure their OS runs on all kinds of different hardware, resulting in all kinds of compatibility requirements.

Cheers ... McBie

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That said, Linux is pretty **** stable on any PC i've run it on

As are the BSDs.

McBie has a valid argument to a point. However, I'd suggest that hardware becomes a problem when you start installing drivers which is partly Microsoft's fault and partly the developer. For instance, I've seen Windows go to its knees after some drivers were installed. Who do I blame? I go with both but I'm more inclined to blame the hardware developer for making terrible drivers.

vansmith said:

Protected memory is not OS X specific. In fact, it's been a part of Windows since NT 3.1.

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Given the existence of the registry, I don't think Windows can be quite as "walled off" as OS X/BSD can be.

If you're talking about "walled off" as something analogous to sandboxing

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Protected memory is a similar concept to sandboxing, but no I didn't use that term and chose not to deliberately, because as you say it's more about security.

Remember, at it's very core, a Mac doesn't have a special motherboard that is somehow unique relative to the rest of the market. It may have back in the day but it doesn't anymore.

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Actually all Mac motherboards are, at least the last time I checked, custom designed by Apple and Intel, so they are, in fact, "special" motherboards in that they can't be swapped out with PC motherboards and you can do with standard motherboards in some models of PC.

That said, my knowledge (which came from hard experience) on Mac RAM standards could be out of date now. But better-quality RAM is always a smart choice on any computer.

chas_m said:

Given the existence of the registry, I don't think Windows can be quite as "walled off" as OS X/BSD can be.

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I think you may have quoted the wrong part of my original post here. That, or we have different understandings of what 'walled off' means.

chas_m said:

Protected memory is a similar concept to sandboxing, but no I didn't use that term and chose not to deliberately, because as you say it's more about security.

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This is a difference in semantics. As Apple makes clear about App Sandbox (the sandboxing strategy for MAS approved apps), it's purpose is to improved security, not stability. Their sandboxing here is designed to limit application access to certain parts of the hardware and/or filesystem. Protected memory on the other hand limits application access to the memory and is used whether or not an application wants it (whereas sandboxing has to be built in).

chas_m said:

Actually all Mac motherboards are, at least the last time I checked, custom designed by Apple and Intel, so they are, in fact, "special" motherboards in that they can't be swapped out with PC motherboards and you can do with standard motherboards in some models of PC.

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Perhaps they are special in that sense but I was suggesting that their compatibility with RAM isn't special in that they can use any type of RAM used elsewhere.

chas_m said:

But better-quality RAM is always a smart choice on any computer.

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Absolutely. One should always try to get the best quality products.

louishen said:

That said, Linux is pretty **** stable on any PC i've run it on

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Isn't that the world upside down ?

Never mind, I think I am having a blond moment

Cheers ... McBie

There's only one reason the mac os never crashes and windows does, it's cos the Mac is better in every way than anything Microsoft attempt to bring out. Fanboys hasn't anything to do with it, good old fashioned common sense does ...

The Mac is, and always has been, the best computer GUI and OS in the history of personal computers imo ......

KarbonKev said:

There's only one reason the mac os never crashes and windows does, it's cos the Mac is better in every way than anything Microsoft attempt to bring out. Fanboys hasn't anything to do with it, good old fashioned common sense does ...

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This is very much a "fanboy" statement. Be careful about making something intrinsically subjective sound as if it were a reflection of objective circumstances.