Hi, Some of the articles of the site claims profiling is essential. Is there any established approach to profiling WEB apps? Or it too much depends on technologies used?
Wikimedia is the platform on which Wikipedia, Wiktionary, and the other seven wiki dwarfs are built on. This document is just excellent for the student trying to scale the heights of giant websites. It is full of details and innovative ideas that have been proven on some of the most used websites on the internet. Site: http://wikimedia.org/
Amazingly TechCrunch runs their website on one web server and one database server, according to the fascinating survey What the Web’s most popular sites are running on by Pingdom, a provider of uptime and response time monitoring. Early we learned PlentyOfFish catches and releases many millions of hits a day on just 1 web server and three database servers. Google runs a Dalek army full of servers. YouSendIt, a company making it easy to send and receive large files, has 24 web servers, 3 database servers, 170 storage servers, and a few miscellaneous servers. Vimeo, a video sharing company, has 100 servers for streaming video, 4 web servers, and 2 database servers. Meebo, an AJAX based instant messaging company, uses 40 servers to handle messaging, over 40 web servers, and 10 servers for forums, jabber, testing, and so on. FeedBurner, a news feed management company, has 70 web servers, 15 database servers, and 10 miscellaneous servers. Now multiply FeedBurner's server count by two because they maintain two geographically separate sites, in an active-passive configuration, for high availability purposes. How many servers will you need and how can you trick yourself into using fewer?
Find Someone Like You and Base Your Resource Estimates Off ThemWe see quite a disparity in the number of servers needed for popular web sites. It ranges from just a few servers to many hundreds. Where do you fit? The easiest approach to figuring out how many servers you'll need is to find a company similar to yours and look how many they need. You won't need that many right away, but as you grow it's something to think about. Can your data center handle your growth? Do they have enough affordable bandwidth and rack space? How will you install and manage all the machines? Who will do the work? And a million other similar questions that might be better handled if you had some idea where you are going.
Get Someone Else to Do itClearly content sites end up needing a lot of servers. Videos, music, pictures, blogs, and attachments all eat up space and since that's your business you have no alternative but to find a way to store all that data. This is unstructured data that can be stored outside the database in a SAN or NAS. Or, rather that building your own storage infrastructure, you can follow the golden rule of laziness: get someone else to do it. That's what SmugMug, an image sharing company did. They use S3 to store many hundreds of terabytes of data. This drops the expense of creating a large highly available storage infrastructure so much that it creates a whole new level of competition for content rich sites. At one time expertise in creating massive storage farms would have been enough to keep competition away, but no more. These sorts of abilities are becoming commoditized, affordable, and open. PlentyOfFish and YouTube make use of CDNs to reduce the amount of infrastructure they need to create for themselves. If you need to stream video why not let a CDN do it instead of building out your own expensive infrastructure? You can take a "let other people do it approach" for services like email, DNS, backup, forums, and blogs too. These are all now outsourcable. Does it make sense to put these services in your data center if you don't need to? If you have compute intensive tasks you can use Amazon services without needing to perform your own build out. And an approach I am really excited to investigate in the future is a new breed of grid based virtual private data centers like 3tera and mediatemple. Their claim to fame is that you can componetize your infrastructure in such a way that you can scale automatically and transparently using their grid as demand fluctuates. I don't have any experience with this approach yet, but it's interesting and probably where the world is heading. If your web site is relatively simple blog then with mostly static content then you can get away with far fewer servers. Even a popular site like Digg has only 30GB of data to store.
How do your resources scale with the number of users?A question you have to ask also is do your resources scale linearly, exponentially, or not much at all with the number of users. A blog site may not scale much with the number of users. Some sites scale linearly as users are added. And others sites that rely on social interaction, like Google Talk, may scale exponentially as users are added. Getting a feel for the type of site you have can help more realistic numbers pop up on your magic server eight-ball.
What's your caching strategy?A lot of sites use Memcached and Squid for caching. You can fill up a few racks with caching servers. How many servers will you need for caching? Or can you get away with just beefing up the database server cache?
Do you need servers for application specific tasks?Servers aren't just for storage, database, and the web servers. You may have a bit of computation going on. YouTube offloads tag calculations to a server farm. GoogleTalk has to have servers for handling presence calculations. PlentyOfFish has servers to handle geographical searches because they are so resource intensive. GigaVox needs servers to transcode podcasts into different formats and include fresh commercial content. If you are a calendar service you may need servers to calculate more complicated schedule availability schemes and to sync address books. So depending on your site, you may have to budget for many application related servers like these. The Pingdom folks also created a sweet table on what technologies the companies profiled on this site are using. You can find it at What nine of the world’s largest websites are running on. I'm very jealous of their masterful colorful graphics-fu style. Someday I hope rise to that level of presentation skill.
That's what people at the NGDC Conference get together and talk about. A lot of interesting subjects: data center virtualization HPC & grid; advanced facilitates management and planning; advanced network and services; applications; data center optimization and security; managing and protecting information. The Grid – Distributed Computing at Scale presentation is an interesting one.
TypePad is considered the largest paid blogging service in the world. After experience problems because of their meteoric growth, they eventually transitioned to an architecture patterned after their sister company, LiveJournal. Site: http://www.typepad.com/
The questions was extracted from: http://highscalability.com/plentyoffish-architecture#comment-126 For startup like Markus, what is the best hosting option (and grow more later)? host your own server or use ISP co-location option? He still has to pay huge money on the bandwidth with that payload, right?
Alan Watts once observed how after we accepted Descartes' separation of the mind and body we've been trying to smash them back together again ever since when really they were never separate to begin with. The database normalization-denormalization dualism has the same mobius shaped reverberations as Descartes' error. We separate data into a million jagged little pieces and then spend all our time stooping over, picking them and up, and joining them back together again. Normalization has been standard practice now for decades. But times are changing. Many mega-website architects are concluding Watts was right: the data was never separate to begin with. And even more radical, we may even need to store multiple copies of data.
The Great Data Ownership Wars: The Database vs. The ApplicationA not so subtle clue as to who won the data wars is to look at the words used. Data that are split up are considered "normal." Those who keep their data whole are considered "de-normal." All right, that's not what those words mean, but it was to good to pass up. :-) Traditionally the database owns the data. Referential integrity, triggers, stored procedures, and everything else that keeps the data safe and whole is in the database. Applications are prevented from screwing up the data. And this makes sense until you scale. Centralizing all behavior in the database won't mega-scale as the web does, which is why Ebay went completely the other way. Ebay maintains data integrity through a service layer that encapsulates all data access. The service layer handles referential integrity, managing replicated copies, doing joins, and so on. It's more error prone than having the database do all this work, but you are able to do scale past what even the highest end databases can handle. All this sharding and denormalization and duplicating at one levels feels so wrong because it's so different than we were all taught. And unless you are a really large website you probably don't need to worry about this level of complexity. But it's a really fascinating and unexpected evolution in design. Scaling to handle the world wide web requires techniques and strategies that are often at odds with our years of experience. It will be fun to see where it all leads.
We're implementing a website which should be oriented to content and with massive access by public and we would need a search engine to index and execute queries on the indexes of contents (stored in a database, most likely MySQL InnoDB or Oracle). The solution we found is to implement a separate service to make index constantly the contents of the database at regular intervals. Anyway, this is a complex and not optimal solution, since we would like it to index in real time and make it searchable. Could you point me to some examples or articles I could review to design a solution for such this context?
Hey, I do have a website that I would like to scale. Right now we have 10 servers but this does not scale well. I know how to deal with my apache web servers but have problems with sql servers. I would like to use the "scale out" system and add servers when we need. We have over 100Gb of data for mysql and we tried to have around 20G per server. It works well except that if a server goes down then 1/5 of the user can't access the website. We could use replication but we would need to at least double sql servers to replicate each server. And maybe in the future it's not gonna be enough we would need maybe 3 slaves per master ... well I don't really like this idea. I would prefer to have 8 servers that all deal with data from the 5 servers we have right now and then we could add new servers when we need. I looked at NFS but that does not seem to be a good idea for SQL servers ? Can you confirm?