Mark's Blog

For a project of mine I have been looking today on key/value stores. Redis, Tokyo Cabinet and Memcache are the popular ones, but I have been interested in benchmarking the distributed species of its kind (“DKVS”). Those are needed in high scalable systems as replacement for traditional databases, which happen not to scale well.

These are the criteria which the DKVS must meet:

1. distribute data amongst one to four nodes (and the more the better)
2. nodes must be able to be added on-the-fly,
3. … and removed on-the-fly
4. data has to be held redundantly, even after removal of a node
5. data access has to be transparent, i.e. every node shall be equal
6. scale with additional nodes – for every additional node there should be an increase of GET and SET operations per second up to the maximum dictated by the hardware and network

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Tags: distributed system, key/value store, nosql, systems architecture

Last Thursday we’ve had a conference about innovativations in IT and systems design here in Hannover. And as its main organizer I held a rather long workshop and speech of about three hours about database (mis)use and which and for what purpose a certain DBMS or storage would fit. In case you missed it, here are the slides (in German). It is about: Read more »

Tags: databases, hanover, Monologe, MySQL, nosql, scalable, systems architecture

latency compared

The problem with RewriteRules and redirects is, that although you save bandwidth because files will be served from CDN, your server will still have to face all requests.

And Every one will result in another request – this time to CDN. In terms of latency you add yours to CDNs and even lose keep-alive transfers. I.e., the browser won’t be able to combine several requests into a single HTTP connection.

The solution is to rewrite all the links at your blog or application so that they point directly to CDN omitting your server.

Tags: CDN, systems architecture

A lot has been written about Wordpress tuning. Unfortunately utilizing CDNs with Wordpress is despite a few plugins still fiddly and requires modifications to themes, links and the such. Yet even a lot of plugins don’t correctly link to their JS files, resulting plugins such as My-CDN not being able to rewrite all links.

Therefore I have written a plugin to hook a rewriter into PHPs ob_start(). Without going further into technical detail, it lets you use a CDN for your Wordpress blog within minutes.

Download the “OSSDL CDN off-linker” here: Wordpress Plugin page.

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Tags: CDN, cloud, know-how, nginx, PHP, server, systems architecture