Scalable Image Storage

Question

I'm currently designing an architecture for a web-based application that should also provide some kind of image storage. Users will be able to upload photos as one of the key feature of the service. Also viewing these images will be one of the primary usages (via web).

However, I'm not sure how to realize such a scalable image storage component in my application. I already thought about different solutions but due to missing experiences, I look forward to hear your suggestions. Aside from the images, also meta data must besaved. Here are my initial thoughts:

1. Use a (distributed) filesystem like HDFS and prepare dedicated webservers as "filesystem clients" in order to save uploaded images and service requests. Image meta data are saved in a additional database including the filepath information for each image.

2. Use a BigTable-oriented system like HBase on top of HDFS and save images and meta data together. Again, webservers bridge image uploads and requests.

3. Use a completly schemaless database like CouchDB for storing both images and metadata. Additionally, use the database itself for upload and delievery by using the HTTP-based RESTful API. (Additional question: CouchDB does save blobs via Base64. Can it however return data in form of image/jpeg etc.)?

Answer 1

We have been using CouchDB for that, saving images as an "Attachment". But after a year the multi-dozen GB CouchDB Database files turned out to be a headache. For example CouchDB replication still has issues if you use it with very large document sizes.

So we just rewrote our software to use CouchDB for image information and Amazon S3 for the actual image storage. The code is available at http://github.com/hudora/huImages

You might want to set up a Amazon S3 compatible Storage Service on-site for your project. This keeps you flexible and leaves the amazon option without requiring external services for now. Walruss seems to become the most popular and scalable S3 clone.

I also urge you to look into the Design of Livejournal with their excellent Open Source MogileFS and Perlbal offerings. This combination is probably the most Famous image serving setup.

Also the flickr Architecture can be an inspiration, although they don't offer Open Source software to the public, like Livejournal does.