Facebook Photo Storage Is No Easy Task

By Justin Lafferty 

Facebook is more than a social network. It’s also increasingly becoming the place where people store their photos for easy sharing. At the Open Compute Summit Wednesday in Santa Clara, Calif., Facebook Vice President of Infrastructure Engineering Jay Parikh (pictured) talked about how the company works to store the more than 240 billion photos on the social network.

Parikh noted that it’s no easy task to store users’ photos. There are more than 240 billion photos on Facebook, with more than 350 million added to the site each day. Parikh said photo storage grows by the insane rate of 7 petabytes per month.

We learned Tuesday how Facebook plans to allow users to search through all of those photos, but storage is just as herculean of a task. Naturally, most of the activity on photos happens shortly after they’re uploaded. Over time, the activity cools off.

However, Facebook has to make sure that the photos users uploaded four years ago still load as quickly as the ones they just posted today. Parikh estimated that about 200 billion photos on Facebook are rarely viewed, if at all. He did point out that when users delete photos from their Facebook pages, they are deleted from the server, as well.

Parikh explained why Facebook has to invest in top-notch, yet energy- and cost-efficient, servers:

We can’t lose any of these photos. Our users expect us to keep these photos for years and decades as they accumulate these lifetimes of memories and experiences with their friends and family. What this actually means is that we have to keep lots of servers around. This costs lots of money, to make sure we have all this data and these memories for our users. The other side of this is that we need to keep a really fast user experience … The problem is we have to use a lot of energy to keep this stuff up and active all the time.

So what Facebook had to do was rethink the traditional server and the traditional data center. Earlier in the Open Compute event, Frank Frankovsky, Facebook’s VP of hardware and design, explained how Facebook has completely changed the way it stores data (by breaking down servers into individual pieces).

To store photos, Facebook relies more on flash storage than hard disks, because it makes it much easier for users to quickly access photos. However, Parikh said it comes at a cost. Facebook is looking at more ways to store the growing amount of data, such as Blu-ray discs, but Parikh told attendees of the conference that more information is needed to see if it makes sense for Facebook from a cost standpoint.

Parikh noted that Facebook’s goals were to maximize space, but minimize the amount of power needed for the data center. He said Facebook was able to achieve this in its data center by storing 1 exabyte of data per room, while using 1.5 megawatts per room.

The cold storage servers that store Facebook’s mounds of data have eight times more storage than traditional servers and store 2 petabytes of data per rack while being powered by 2 kilowatts per rack. Parikh said that the cold storage rack is one-third cheaper than a conventional storage center, while Facebook’s data centers in general are operated at one-fifth of the cost of a traditional data center.

Readers: How often do you upload photos to Facebook?