Running those 1.3 billion Hotmail inboxes

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Arthur de Haan’s post back on Dec 22nd made for interesting reading purely regarding the scale of Hotmail.

  • We are a worldwide service, delivering localized versions of Hotmail to 59 regional markets, in 36 languages.
  • We host well over 1.3 billion inboxes (some users have multiple inboxes)
  • Over 350 million people are actively using Hotmail on a monthly basis (source: comScore, August 2009).
  • We handle over 3 billion messages a day and filter out over 1 billion spam messages - mail that you never see in your inbox.
  • We are growing storage at over 2 petabytes a month (a petabyte is ~1 million gigabytes or ~1000 terabytes).
  • We currently have over 155 petabytes of storage deployed (70% of storage is taken up with attachments, typically photos).
  • We’re the largest SQL Server 2008 deployment in the world (we monitor and manage many thousands of SQL servers).

Aside from the fact that I’ve always found it odd that product teams in Redmond refer to themselves and their products as “we”, those numbers are HUGE. It’s a fascinating and unusually candid insight in to what it takes to make these services tick. The service has four copies of your data for redundancy as an example.

When people say Microsoft is late to the cloud, I point them to Hotmail.