Evernote Architecture - 9 Million Users and 150 Million Requests a Day

Cool to see that they use Stripes as their Java web framework. Stripes doesn't get anywhere near the attention/respect it deserves. It's definitely the simplest, most easy-to-use framework in the Java space IMO.

I love how successful architectures like this really cut down a business to it's core offering -- which in Evernote's case, is object storage.

I may have missed this, but I didn't see anything indicating Evernote has any off-site redundancy, in case of earthquake disruption. The Evernote "Architectural Digest" blog entry linked in the OP says "All of these servers are racked in a pair of dedicated cages at our data center in Santa Clara, California." (I've been a paid Evernote subscriber for a couple of years or so.)

User data is stored on four different enterprise drives across two different physical servers. Nightly backups copies data over a dedicated 1Gbps link to a secondary data center. This kinda scares me. Is this a real backup going to removable storage stored in a secure backup facility? If it's being synced via a dedicated line, why is it nightly instead of continuous? And if those four drives are the only source for production user data, isn't it likely a storm of writes could cause a severe bottleneck? (assuming SCSI drives, ~200 ops * 4 = 800 ops total, or with SSDs, 2400 ops... will they ever write more than 2400 times a second?)

Also, an extra layer (memcached) in front of mysql for caching requests could save them lots of nodes if reads are dragging down performance/requiring more nodes to spread read load.

150 million requests per day is just under 2 requests a second... 100k users/shard is also hardly impressive even if you account for 2x or 3x replication.

I hate to sound like a dick, but anyone who has dealt with large scale web apps would consider this a starting point, not worthy of a architecture presentation.

EDIT: Ah ha. Having never used Evernote before, they didn't make it very clear that they are essentially trying to build a SAN. I assumed they were storing plain text notes like stickies.