Amazon EC2 cloud is made up of almost half-a-million Linux servers

Amazon EC2 cloud is made up of almost half-a-million Linux servers

Summary: Recent research indicates that Amazon's EC2 cloud is made up of almost half-a-million servers--each of them running a variation of Red Hat Linux for their base operating system.


Almost half-a-million Amazon cloud servers run Linux every day.

Almost half-a-million Amazon cloud servers run Linux every day.

We know that Linux on servers is big and getting bigger. We also knew that Linux, thanks to open-source cloud programs like Eucalyptus and OpenStack, was growing fast on clouds. What he hadn't know that Amazon's Elastic Compute Cloud (EC2), had close to half-a-million servers already running on a Red Hat Linux variant.

Huang Liu, a Research Manager with Accenture Technology Lab with a Ph.D. in Electrical Engineering whose has done extensive work on cloud-computing, analyzed EC2's infrastructure and found that Amazon EC2 is currently made up of 454,400 servers.

While Amazon has never officially said what it's running as EC2's base operating system, it's generally accepted that it's a customized version of Red Hat Enterprise Linux (RHEL). On top of that, for the virtual machines, Amazon uses the Xen hypervisor to host Linux; OpenSolaris; Solaris; Windows 2003 and 2008; and FreeBSD and NetBSD virtual machine instances.

Amazon also doesn't talk about how many servers their popular cloud is made up of, so Huang had to work it out. He explained, "Figuring out EC2's size is not trivial. Part of the reason is that EC2 provides you with virtual machines and it is difficult to know how many virtual machines are active on a physical host. Thus, even if we can determine how many virtual machines are there, we still cannot figure out the number of physical servers. Instead of focusing on how many servers are there, our methodology probes for the number of server racks out there."

Huang continued, "It may sound harder to probe for the number of server racks. Luckily, EC2 uses a regular pattern of IP address assignment, which can be exploited to correlate with server racks. We noticed the pattern by looking at a lot of instances we launched over time and running traceroutes between our instances."

Then "Understanding the pattern allows us to deduce how many racks are there. In particular, if we know a virtual machine at a certain internal IP address (e.g.,, then we know there is a rack using the /22 address range (e.g., a rack at 10.2.12.x/22). If we take this to the extreme where we know the IP address of at least one virtual machine on each rack, then we can see all racks in EC2."

By itself, though, that's not enough. You could use try to use port-scanning to work ot how many servers there are, but that would violate Amazon's terms of service. So instead, since each Amazon Web Services (AWS) "instance also has an external IP address. … we can leverage DNS translation to figure out the internal IP addresses."

With that data, he was able to work out the number of server racks. With this he then just multiplied by the number of physical servers on the rack. "Unfortunately, we do not know how many physical servers are on each rack, so we have to make assumptions. We assume Amazon has dense racks, each rack has 4 10U chassis, and each chassis holds 16 blades for a total of 64 blades/rack."

So it is that Huang worked out how many servers there are in the EC2 cloud. It's an impressive achievement for him and it's an impressive example of just how important Linux is in both server and clouds.

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Topics: Software, Amazon, Hardware, Linux, Open Source, Operating Systems, Servers, Virtualization

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  • Amazon EC2 cloud is made up of almost half-a-million Linux servers

    That's a lot of servers just to keep a web site running. What was it that I was saying about it taking more linux servers to perform tasks than its competitors? I bet that crow tastes pretty good right about now.
    Loverock Davidson-
    • You forgot to mention the TelNet port thingy

      Imagine 500,000 telnet ports open all at once. That's a problem :/
      Dietrich T. Schmitz *Your
      • You had to say Telnet didn't you?

        I'd almost recovered from the 1990s, thanks a lot!
    • Web site?

      Do you even know what the EC2 cloud is? It does not run the Amazon web site, it is a service.
      • But you don't know that...

        ... Loverock is the forum's jester. Here Loverock, help yourself to the wine, you made a fine joke.
      • That was by design. You've been snared.

        Dietrich T. Schmitz *Your
    • The quality of the blogs and trolls here on ZDNet site is amazing

      I mean on all sides. Windows/Linux/Apple.
    • You don't understand the EC2

      Amazon EC2 isn't designed to support "", or "a website". EC2 is a service provided to businesses. People rent "servers" from Amazon. It's unique in that it's "elastic", meaning that people purchase instances at a pay per instance, per hour rate, which can dyanamically be up or down-scaled according to traffic needs. So, they are serving countless business with many virtual private servers on those half-million Linux boxes. I'd also suggest you spend some time getting to know GNU/Linux. I can tell based on your comments that you've probably never left a KDE or GNOME desktop environment at best.
      Travis Nesbit
  • Not surprising.

    Goes back to the old saying. "Linux/Unix is for servers. Macs are for graphics. Windows is for solitaire."

    Most IT admins I know agree that any service critical to business function should be ran on Unix/Linux. The cloud is a service that must be reliable, so it is no surprise they run linux. Same goes for Web Servers, FTP servers, Load Balancers, or anything else that needs high availability.
    • And most IT admins I know say

      that any service critical to business function should be ran on Windows.

      Guess it depends on what admins you talk to.
      William Farrel
      • What, Like Azure ?

        MS muppets can't even code for a leap year.
        Alan Smithie
      • Unnecessary, but funny.

        I realize I shouldn't encourage taking cheap shots at one another in the forums, because it degrades the forum ... but I really did laugh out loud when I read "MS muppets can't even code for a leap year."

        Thanks for the laugh. :-)
  • Time for a real server OS !

    Maybe Amazon could move to Windows Server, it will probably take half of them to do the same workload, and with Red Hat pricing it will probably be more than 50% cheaper to boot.
    • "realm server OS"?

      The six MSCE's that worked in the IT dept that serviced the 500 workstations where I worked said that one Linux server could do the work of four Windows servers, never had to be rebooted on weekends to restore their speed, and never got infected. They used a Linux gateway to the Internet, running $28K of AV software to keep the Windows boxes safe. But, that was just what they said. What do I know, I was only a programmer.
      • Mcse Certification is outdated

        They should maybe update their skillset. Rebooting to gain performance ? Infected ? I manage hundreds of servers, and to date none has been infected, none needed a reboot to gain performance. Of course we all know Linux machines are not immune to vulnerabilities, quite a few have been turned into zombies when apache had a few problems. Even the Linux foundation was down for weeks on end, yeah it is all looking good !
  • Amazon EC2 cloud is made up of almost half-a-million Linux servers

    Kudos Amazon EC2 and Linux servers.

  • Big mass debate going on here!

    • It starts with the first troll

      SJVN, and just rolls along. From what I understand, it's the only reason SJVN is here.
      William Farrel
      • Beside the fact that you show up using an alias, what's your excuse?

        Dietrich T. Schmitz *Your
  • SJVN = crap articles

    MS cloud /hotmail/bing may contains more than 10 million Windows servers, but does anybody pound their chest about it? NO.

    SJNV, please learn to write mature articles.