Tag: Amazon EC2

Upgrading Amazon EC2 instance type

By now everybody knows that one of the major benefits to using cloud services rather than hosting on your own hardware is the ease to scale quickly.  Many web applications and large companies benefit from this, but what about smaller customers?  How about a single server?

Well, today one of our web servers was experiencing some pick loads.  It hosts a whole array of small websites built with WordPress, CakePHP, and other popular tools.  There was no time to update all these projects to work with multiple web servers.  And even redeploying them to multiple individual servers would have taken a few hours.  Instead, we’ve decided to upgrade the server hardware.

Pause for a second and imagine the situation with your own server.  Or a dedicated hosting account for that matter.  So much to configure.  So much to backup and restore.  So much to test.

Here’s how to do it, if your projects are on the Amazon EC2 instance (our was also inside a virtual private cloud (VPC), but even if it wasn’t, the difference would be insignificant):

  1. Login to the Amazon AWS console.
  2. Navigate to the Amazon EC2 section.
  3. Click on Instances in the left sidebar.
  4. Click on the instance that you want to upgrade in the list of your instances.
  5. Click Actions -> Instance State -> Stop.
  6. Wait a few seconds for the instance to stop.  You can use the Refresh button to update the list.
  7. (While your instance is still selected in the list of instances:) Click Actions -> Instance Settings -> Change Instance Type.
  8. In the popup window that appeared, select an Instance Type that you want.
  9. Click Apply.
  10. Click Actions -> Instance State -> Start.
  11. Wait a few seconds for the instance to start.
  12. Enjoy!

The whole process literally takes under two minutes.  You get exactly the same configuration – hostname, IP addresses (both internal and external), mounted EBS volumes, all your OS configuration, etc.  It’s practically a reboot of your machine. But into a different hardware configuration (CPU/RAM).

Coincidentally, earlier this morning I had to pack up a rack-mountable server – screws, cables, dusty boxes, the whole shebang.  It’s been a while since I’ve done that last time.

But I can tell you that I much prefer clicking a few buttons and moving on with my day.  Maybe I’m just not the hardware type.

 

WTF with Amazon and TCP

Here goes the story of me learning a few new swear words and pulling out nearly all my hair.  Grab a cup of coffee, this will take make a while to tell…

First of all, here is a diagram to make things a little bit more visual.

wtf

As you can see, we have an office network with NAT on the gateway.  We have an Amazon VPC with NAT on the bastion host.  And then there’s the rest of the Internet.

The setup is pretty straight forward.  There are no outgoing firewalls anywhere, no VLANs, no network equipment – all of the involved machines are a variety of Linux boxes.  The whole thing has been working fine for a while now.

A couple of weeks ago we had an issue with our ISP in the office.  The Internet connection was alive, but we were getting extremely high packet loss – around 80%.  The technician passed by, changed the cables, rebooted the ADSL modem, and we’ve also rebooted the gateway.  The problem was fixed, except for one annoying bit.  We could access all of the Internet just fine, except our Amazon VPC bastion host.  Here’s where it gets interesting.

Continue reading WTF with Amazon and TCP

Amazon Makes It Almost Impossible To Calculate Their “Virtual CPU” Equivalent

So, it looks like I’m not the only one trying to figure out Amazon EC2 virtual CPU allocation.  Slashdot runs the story (and a heated debate, as usual) on the subject of Amazon’s non-definitive virtual CPUs:

ECU’s were not the simplest approach to describing a virtual CPU, but they at least had a definition attached to them. Operations managers and those responsible for calculating server pricing could use that measure for comparison shopping. But ECUs were dropped as a visible and useful definition without announcement two years ago in favor of a descriptor — virtual CPU — that means, mainly, whatever AWS wants it to mean within a given instance family.

A precise number of ECUs in an instance has become simply a “virtual CPU.”

Amazon EC2 t2.nano instances

If you thought t2.micro was a tiny machine, I have news for you – Amazon announced t2.nano instance type.  It features 512 MB of RAM, 1 vCPU, and up to two Elastic network interfaces.  Price for on-demand instance – $0.0065 per hour.

This instance type is perfect for small websites, developer and testing environments, and other tasks which don’t require a lot of resource.

CPU Steal Time. Now on Amazon EC2

Yesterday I wrote the blog post, trying to figure out what is the CPU steal time and why it occurs.  The problem with that post was that I didn’t go deep enough.

I was looking at this issue from the point of view of a generic virtual machine.  The case that I had to deal with wasn’t exactly like that.  I saw the CPU steal time on the Amazon EC2 instance.  Assuming that these were just my neighbors acting up or Amazon having a temporary hardware issue was a wrong conclusion.

That’s because I didn’t know enough about Amazon EC2.  Well, I’ve learned a bunch since then, so here’s what I found.

Continue reading CPU Steal Time. Now on Amazon EC2