平衡httpd和保存项目文件

Question

I have this project I'm working on for already 3years+. It's big. And I'm thinking of future updates / scenarios as I am finishing it up, as well as work on my final touchs.

I recently looked over the net into Apache / webserver daemon balancing, which brings to life more than 1 server that serves the files with threads, for balancing purposes.

My question is, as I am saving files (images) with my projects in selected folders in the linux box :

when page is served from another secondary server (balancing), and user needs to save the picture, where does he save it ? I need to know this so if I end up with multiple httpd servers, I need to know all the files saved by my users are where they should be, so the app displays them neatly.

Answer 1

There are a lot of solutions here, depending on budget, skills, etc. First off your load balancing software should have the facility to make sure a session is sticky so that your user doesn't get switched to a different server mid way through the upload, or pick a server to handle all of the uploads. Once the image is uploaded you could: (I only have experience with linux when it comes to servers, you didn't say which OS)

• FTP the image to the other servers : http://php.net/manual/en/book.ftp.php
• use rsync to copy between servers, either triggered by the upload or on a scheduled cron http://rsync.samba.org/
• upload the images to a CDN like cloudfront or rackspace files and serve them from there
• use grid fs never tried it personally, but sounds very fancy: http://docs.mongodb.org/manual/faq/developers/#faq-developers-when-to-use-gridfs

• use network attached storage - could get pricey

  When you want to keep your files and metadata automatically synced and deployed across a number of systems and facilities.

A note on uploading to CDN, if the local copy dies it might be expensive to download them all in one go, so not necessarily a solution to use by itself

Best not use to an NFS share (mounting the dir of the images across the network) as that means if the one server goes down best case no images served, worst it drags the other servers down with it (had that happen!)

DB update

I had discounted storing blobs a long time ago because in the project where I need to have images on multiple servers we have portrait, landscape and square versions in about 6 sizes each (articles, galleries, list pages, mobile etc) but now that I think of it. I might look into just storing the largest/original in the DB and generating the others on demand with caching, that might work quite well