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StackOverflow Update: 560M Pageviews a Month, 25 Servers

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Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#4
"One problem is not many tests. Tests aren’t needed because there’s a great community... If users find any problems with it they report the bugs that they’ve found."

I'm often surprised at the paucity of test-coverage in relatively large companies.

http://nerds.airbnb.com/testing-at-airbnb/

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#5
> With their SQL Servers loaded with 384 GB of RAM and 2TB of SSD, AWS would cost a fortune.

I have next to zero experience with server administration, but 384GB seems like a lot to me. Is that common for production servers for popular web services? Do you need a customized OS to address that much memory? Seems like you'd really need to beef up the cache hierarchy make 0.38TB of RAM fast.

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#6
post #2

I've recently started using their micro-ORM Dapper, and I like it a lot. I get the performance of hand-coded SQL, but without the tedious mapping from SqlDataReader to my entity.

Dapper is great - I promptly dumped NHibernate and Entity Framework for it. It's the only ORM I've found that makes it trivially easy (as it should be) to use stored procedures and views in queries.

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#7
post #3

Makes me wonder why smaller website teams need dozens of engineers to keep their infinitesimally smaller app running.

I personally think it's due to overly complex applications and systems with many moving (and breaking) parts.

Also StackOverflow often practices "scale-up" instead of "scale-out".

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#8
post #5

> With their SQL Servers loaded with 384 GB of RAM and 2TB of SSD, AWS would cost a fortune. I have next to zero experience with server administration, but 384GB seems like a lot to me. Is that common for production servers for popular web services? Do you need a customized OS to address that much memory? Seems like you'd really need to beef up the cache hierarchy make 0.38TB of RAM fast.

It's not a server, but I've seen machines used in physics simulations have something on the order of 256 GB RAM in them. As far as I know they cost maybe $20k-$30k, so not absurdly expensive.

I don't think addressing that memory is a problem on any x64 architecture. Windows Server 2012 has a 4TB upper limit on RAM, apparently [1], and as far as I can tell there's no reason for this other than product differentiation between different "levels" of the operating system.

1. http://msdn.microsoft.com/en-us/library/windows/desktop/aa36...

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#9
post #5

> With their SQL Servers loaded with 384 GB of RAM and 2TB of SSD, AWS would cost a fortune. I have next to zero experience with server administration, but 384GB seems like a lot to me. Is that common for production servers for popular web services? Do you need a customized OS to address that much memory? Seems like you'd really need to beef up the cache hierarchy make 0.38TB of RAM fast.

Linux (SuSE enterprise something, possibly with a custom kernel, I’m just a user, not admin) runs just fine on 5.2TB machine, though I can easily imagine you’d have problems if you tried it with, say, DOS :)

The system obviously behaves a bit different from a standard desktop machines, e.g. different areas of RAM are differently fast, depending on the core on which your current process runs, you need to disable individual CPU lines displayed in top etc., but apart from these, mostly everything seems “normal” to me.

Re: StackOverflow Update: 560M Pageviews a Month, 25 Servers

#10
post #5

> With their SQL Servers loaded with 384 GB of RAM and 2TB of SSD, AWS would cost a fortune. I have next to zero experience with server administration, but 384GB seems like a lot to me. Is that common for production servers for popular web services? Do you need a customized OS to address that much memory? Seems like you'd really need to beef up the cache hierarchy make 0.38TB of RAM fast.

384 gigs is pretty common these days. With Windows, you need at least the server edition to address that much, but if you're running a server, you're not gonna be using the desktop versions of the OS anyways. Pretty much everything else, it's just plug and play. The RAM is quite a bit if you're doing a typical cloud deployment, but SO seems to be more in the model of making sure all your eggs are in a really strong basket. Besides, at the end of the day, RAM tends to be a lot cheaper than lag.
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