# Blade servers and databases

**URL:** <https://boards.straightdope.com/t/blade-servers-and-databases/495002>\
**Category:** Factual Questions\
**Created:** [May 1, 2009, 6:54pm UTC](https://boards.straightdope.com/t/blade-servers-and-databases/495002 "2009-05-01T18:54:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Sefton](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Sefton](https://boards.straightdope.com/u/Sefton)\
**Post date:** [May 1, 2009, 6:54pm UTC](https://boards.straightdope.com/t/blade-servers-and-databases/495002/1 "2009-05-01T18:54:59Z")

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I’m a web programmer, not a server admin, but one thing has always puzzled me: if each blade in a blade server is a separate computer and there’s no central memory, how does a blade server provide access to information in a main database? Do you install the database on each blade and replicate all the changes between them?

For example, let’s say a blade server provides access to Wikipedia. How are Wikipedia requests distributed between the blades? Does one blade handle A-D requests while another blade handles E-H?

Server hardware has always fascinated me. If anyone wants to share how their system is configured and how well it works, I’d be happy to know.

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**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\
**Post date:** [May 1, 2009, 7:46pm UTC](https://boards.straightdope.com/t/blade-servers-and-databases/495002/2 "2009-05-01T19:46:30Z")

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You might find this interesting: [Wikimedia servers - Meta](http://meta.wikimedia.org/wiki/Wikimedia_servers)

Typically, the requests are handled by a cluster of web servers, that connect over a fast LAN to a cluster of database servers, which actually store all the data. For a global organisation, the database servers might be replicated across several locations, each with a web server front-end. Hardware load balancers spread the workload across the servers in a cluster, on a round-robin or least-busy basis, to keep all the boxes humming and as many active connections as possible. Lots of caching at various levels helps reduce latency, and the back-end servers are usually connected to a fast SAN or equivalent, using replication technology to keep all the servers in sync. Each server may or may not contain a complete copy of the database.

That’s a very, very simple setup; in practice it might be far more complex.

More info here: [A Look Inside Wikipedia's Infrastructure | Data Center Knowledge | News and analysis for the data center industry](http://www.datacenterknowledge.com/archives/2008/06/24/a-look-inside-wikipedias-infrastructure/)

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**Author:** ![Sefton](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Sefton](https://boards.straightdope.com/u/Sefton)\
**Post date:** [May 1, 2009, 7:59pm UTC](https://boards.straightdope.com/t/blade-servers-and-databases/495002/3 "2009-05-01T19:59:12Z")

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Thanks **Dervorin**! Those are great links.