Scalable virus scanning for web-applications

Hi, We're looking for a highly scalable way of scanning documents being uploaded and downloaded from our web application. I believe services like gmail and hotmail are using bespoke solutions from companies like Trend, but are there some quality "off the shelf" products out there that can easily be scaled out and have a "loose" API (HTTP based) for application integration? Once again, thanks for any input.

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Secure Remote Administration for Large-Scale Networks

This website has been a great resource for helping me to understand the successful (and failed) scalable network designs from organizations that have actually done it, but I haven't seen any explicite explanations about secure remote administration of these systems. I understand that the *nix people love to SSH, and the windows gang has their RDP, but how does one go about creating a network architecture that both allows one to manage their systems and does its best to avoid hacker interest? As I imagine, no big website will have the SSH/RDP/FTP ports open on the web server, so how is it that they go about remotely administering their geographically diverse groups of servers securely?

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UK Based CDN

Hi, I was wondering if I could borrow the collective minds of you all to draw up a list to the CDN's that you'd use/do use in the UK. If they're outside the UK but have decent support then also include. The service must be cheap and not require a huge setup fee, it's really only for a small time business; it shares video & high-res pics so mass cheap storage is a must and wondered whether you guys had any ideas, also costs? Mass storage isn't cheap in the UK compared to the states, for example, unless I go colo but as I say, it's a small setup but happens to require a fair bit of space. Would S3 be a good starting point? What is the service like? I hear mixed reviews about it. Many thanks, Jim

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Scaling an image upload service

Hi, First of all I want to to say that this is an extremely interesting and informative website. i have enjoyed reading the various posts on how the big sites scale to meet the needs of their customers. The service we are developing is a webcam service. The client application sends images to the server via HTTP POST and they are saved in folder specified by the users id. When a new image is sent to the server it will overwrite the current image. Users can then view the images via our web server. Ideally we want the images to upload as quickly as possible and allow users to view them as quickly as possible. Would I be correct to assume that when the number of uploading clients exceeds the capability of the server the only way to scale is to add more hardware. Also I assume that to use HTTP accelerator caches will not speed up viewing the images as the new images will invalidate the cache. I appreciate any input on the subject.

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High performance file server

What have bunch of applications which run on Debian servers, which processes huge amount of data stored in a shared NFS drive. we have 3 applications working as a pipeline, which process data stored in the NFS drive. The first application processes the data and store the output in some folder in the NFS drive, the second app in the pipeline process the data from the previous step and so on. The data load to the pipeline is like 1 GBytes per minute. I think the NFS drive is the bottleneck here. Would buying a specialized file server improve the performance of data read write from the disk ?

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Simple NFS failover solution with symbolic link?

I've been trying to find a high availability file storage solution without success. I tried GlusterFS which looks very promising but experienced problems with stability and don't want something I can't easily control and rely on. Other solutions are too complicated or have a SPOF. So I'm thinking of the following setup: Two NFS servers, a primary and a warm backup. The primary server will be rsynced with the warm backup every minute or two. I can do it so frequently as a PHP script will know which directories have changed recently from a database and only rsync those. Both servers will be NFS mounted on a cluster of web servers as /mnt/nfs-primary (sym linked as /home/websites) and /mnt/nfs-backup. I'll then use Ucarp (http://www.ucarp.org/project/ucarp) to monitor both NFS servers availability every couple of seconds and when one goes down, the Ucarp up script will be set to change the symbolic link on all web servers for the /home/websites dir from /mnt/nfs-primary to /mnt/nfs-backup The rsync script will then switch and the backup NFS will become primary and backup to the previous primary when it gets back online. Can it really be this simple or am I missing something? Just setting up a trial system now but would be interested in feedback. :) Also, I can't find out whether it's best to use NFS V3 or V4 these days?

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How to build a real-time analytics system?

Hello everybody! I am a developer of a website with a lot of traffic. Right now we are managing the whole website using perl + postgresql + fastcgi + memcached + mogileFS + lighttpd + roundrobin DNS distributed over 5 servers and I must say it works like a charm, load is stable and everything works very fast and we are recording about 8 million pageviews per day. The only problem is with postgres database since we have it installed only on one server and if this server goes down, the whole "cluster" goes down. That's why we have a master2slave replication so we still have a backup database except that when the master goes down, all inserts/updates are disabled so the whole website is just read only. But this is not a problem since this configuration is working for us and we don't have any problems with it. Right now we are planning to build our own analytics service that would be customized for our needs. We tried various different software packages but were not satisfied with any of them. We want to build something like Google Analytics so it would allow us to create reports in real-time with "drill-down" possibility to make interactive reports. We don't need real-time data to be included in report - we just need a possibility to make different reports very fast. Data can be pre-processed. For example right now we are logging requests into plain text log files in the following format: date | hour | user_id | site_id | action_id | some_other_attributes.. There are about 8 - 9 million requests per day and we want to make real-time reports for example: - number of hits per day (the simplest) - number of hits by unique users per day - number of hits by unique users on specific site per day - number of distinct actions by users on specific site during defined period (e.g. one month, period of X months...) etc. You can display any type of report by combining different columns as well as counting all or only distinct occurrences of certain attributes. I know how to parse these log files and calculate any type of report I want, but it takes time. There are about 9 million rows in each daily log file and if I want to calculate monthly reports I need to parse all daily log files for one month - meaning I have to parse almost 300 million of lines, count what I want and then display the summary. This can take for hours and sometimes it has to be done in more than one step (e.g. calculating a number of users that have been on site_id=1 but not on site_id=2 - in this case I have to export users on site 1, export users on site 2 and then compare results and count the differences). If you take a look at Google Analytics it calculates any type of similar report in real-time. How do they do it? How can someone form a database that could do something like that? If I put 300 million of rows (requests per month) into the Postgres/MySQL table, selects are even slower than parsing plain text log files using Perl... I am aware that they have a huge amount of servers but I am also aware that they have even bigger amount of hits per day. I have a possibility to store and process this kind of analytics on multiple servers at the same time but I don't have enough knowledge how to construct a software and database that would be able to do a job like this. Does somebody have any suggestion? A simple example would be great! We already managed to make some sort of a database for site_id+action_id drilldown but the problem is with "unique users" which is THE information that we need all the time. To calculate unique users during certain period you have to count all the distinct user_ids during that time period. E.g.: select count(distinct user_id) from ... where date>='2008-04-10' and date <='2008-04-18' - with a 9million rows per day this statement would take about two minutes to complete and we are not satisfied with it. Thank you for any hint!

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Mysql scalability and failover...

Hi, I am an owner of an large community website and currently we are having problems with our database architecture. We are using 2 database servers and spread tables across them to divide read/writes. We have about 90% reads and 10% writes. We use Memcached on all our webservers to cache as much as we can, traffic is load balanced between webservers. We have 2 extra servers ready to put to use! We have looked into a couple of solution so far: Continuent Uni/Cluster aka Sequoia -> Commercial version way too expensive and Java isn't as fast as it suppose to be. MySQL Proxy -> We couldn't find any good example on how to create a master - master with failover scenario. MySQL Clustering -> Seems to be not mature enough, had a lot of performance issues when we tried to go online with it. MySQL DRDB HA -> Only good for failover, cannot be scaled! MySQL Replication -> Well don't get me started ;) So now I turn to you guys to help me out, I am with my hands in my hair and see the site still growning and performance slowly getting to its limit. Really need your help!! HELP!

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Development of highly scalable web site

Not sure if this is the right place to post this but here goes anyway. We are looking to hire an outside firm to help with development of a scalable and potentially high-traffic web site. We are not looking for an individual but rather a firm with enough well rounded expertise to help us with various aspects of this. Basic requirements: LAMP stack or other open source solution Very proficient in cross-browser web development Flex/AIR development for RIA Java/C/C++ proficiency Expertise with Comet and push server technology Experience with development of high-traffic web sites Use of Amazon Web Services infrastructure a plus If anyone knows of consulting firms that can take on such a project, I would appreciate your feedback. TIA

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How to update video views count effectively?

Hi, I am building a video-sharing site and I'm looking for an efficient way to update video views count. The easiest way would be to perform an SQL update to increase the "views" counter every time a video is viewed, but naturally I want to avoid DB write access as much as possible. I am looking for an efficient temporary storage to which I could connect and say "increment views of video X". Every so often I would save the changes to my main database, and remove the counter from this temporary storage. I am having a hard time finding such temporary storage, however. My first thought was memcache, but it's not ideal as I wouldn't like to lose the data if memcache goes down. Also, memcache's increment command requires that the key is already present - that means that every time a video is viewed, I would have to check if the key already exists in memcache, before I can actually send the increment command. What do people use to solve this kind of issues? Kind regards, Tomasz

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