Thursday, November 13, 2008

Presentation on how Microsoft deployed Exchange 2007

Harold Wong presented a seminar on how Microsoft deployed Exchange 2007 internally and it was an interesting presentation. They have 150,000 users worldwide so the scale is quite large but they took the time to do some price/performance/benefit experiments that produced some surprising conclusions. The ones that seemed unusual to me are:

  • Exchange 2007 mailbox servers are typically 2 CPU / dual core servers, 24 gigs of RAM, and large Direct Attached SCSI arrays with 2.5 inch SFF, 10,000 RPM, 146 gigabyte disks.
  • They are not Window clustered servers. Each server is part of an Exchange 2007 CCR cluster but the server itself is not a “classic” cluster.
  • There is no SAN and no shared storage.
  • With 10 terabytes of raw disk space, they have one server support between 4,000 and 6,500 users with 1gig and 2 gig mailbox limits
  • Site to site replication via an SCR cluster is only partially implemented.
  • They have chosen not to split CCRs across a WAN because of the way CAS servers and hub servers load balance. Both parts of the CCR need sit on the same subnet and AD site and their associated hub servers need to do the same. Since the CAS servers load balance automatically, roughly half of your clients will always be crossing the WAN to get from the CAS server to the mailbox server.
  • Tests with 5400 RPM SATA arrays showed that Exchange could easily run on very slow hardware. They felt that they still kept the 10,000 rpm SCSI because of they could support a higher number of users at their preferred minimum response time for lower cost per user with the SCSI compared to the SATA. However, for environments with less than a thousand mailboxes, SATA would be perfectly acceptable for most organizations. These tests were run several years ago so newer SATA drives are probably even better values now.

I also attended a session on deploying large mailboxes in an economical way. This presentation referenced a lot of statistics produced by Microsoft and Dell about costs and impacts. Based on that data, the cost per user for 2 gigabyte mailboxes was only 25% higher than the cost per mailbox at 250 megabytes. The Microsoft design team is currently testing with 10 gigabyte mailbox limits to see what the impacts are to operations. They brought up some interesting points about large mailboxes that I hadn’t thought of:

  • If you give them a large mailbox, there is no archive, everything is live. If everything is “live”, then everything is reachable from every access medium (OWA, Outlook, OMA, etc.)
  • Server side data is backed up, local data is not
  • Server side data is discoverable in a lawsuit, local data is not
  • Server side data is access protected, local data is not.

I think I will propose a 10 gigabyte structure for my current company just to see what the cost impacts really are.

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