I am planing on using aws free tier for some testing of apps. I am dividing my time (750 hours a month)between a windows instance (30gb ebs default) and ubuntu instance (8gb ebs default ) using lambada functions and cloud watch.

Free tier documentation says that free tier gets 30 gb of storage right? This means I would need to divide my storage between both instances so I don't get charged for my free tier monthly usage correct? What's the best way to have two instances and stay within free tier for storage?


What Free Tier Provides

Free tier gets 30GB of EBS storage, plus a lot of other things, including:

  • A single t2.micro EC2 instance
  • An elastic load balancer
  • 5GB of EFS storage
  • An RDS relational database instance, with 20GB of storage and a set number of IOPS
  • DynamoDB no-sql database, 25GB plus read/write capacity
  • Lambda serverless computing

Plus a whole host of other services. You can see the list here.

What is Free Tier For

The free tier seems to be designed to let you run single instance, with associated services, to help you work out if AWS is right for your workload. I guess they're also trying to get you hooked so you start paying once the year runs out.

Staying Within Free Tier

The best way to stay within this 30GB is to allocate 30GB or less to your EBS volumes. For example, two 15GB volumes, or one 10GB and one 20GB. Personally I would leave a small buffer if you really want to avoid being charged - perhaps try to use less than 29GB. AWS often use GiB, which is different from GB, but the free tier does say GB. A GiB is larger than a GB.

You can use CloudWatch to monitor your resource usage.

Operating Systems and EBS Disk Space

You said Windows server is 19GB, which fits within your free tier. Linux images are significantly smaller than Windows. Since you can only run one instance for free, and each is less than 30GB, this seems fine.

If you want to run two instances you obviously just need to keep the disk space down. With Windows you can do things like use minimal swap space, disable things like hibernation, uninstall components you don't need, etc.

Though you can resize the EBS volume, reducing the size looks problematic, if it's possible at all. I initially suggested creating a large volume, optimizing windows, then reducing the size, but as pointed out by Michael I think you should start with the volume size you need.

Since you have 5GB of EFS included you can consider putting some of your data here. Note that once free tier finishes EBS costs $0.10 per GB but EFS is $0.30 per GB. EBS resizes in a single AZ (data centre), EFS stores data in multiple AZs (data centers). EFS scales to very high throughput as well.

AWS Bill

Will likely still have an AWS bill if you use services outside the free tier. For example you will likely want to take EBS snapshots, which are volume backups. You get 1GB free, but if you use 30GB of disk your compressed snapshots will be significantly more than 1GB.

  • Thanks Tim. Very helpful. Windows Server base instance takes around 19 gb as it is. Unless I can shave the storage down. Free tier is really just setup for 1 instance it seems like for it to be actually free. Apr 17 '17 at 22:42
  • 1
    I've expanded my answer. Have a look at the "Operating Systems and EBS space" section, particularly around resizing EBS volumes.
    – Tim
    Apr 17 '17 at 23:06
  • @Tim, I might be wrong, but "If your Amazon EBS volume is attached to a current generation EC2 instance type, you can increase its size..." suggests that shrinking an EBS volume isn't a thing. AFAIK, you'd need to detach, resize the filesystem and repartition the volume, leaving unallocated space at the end, and do a dd style bit copy of the first blocks of the old volume onto a new one. Theoretically possible, but messy. Apr 18 '17 at 9:29
  • @Michael-sqlbot you're probably right, extending looks easy, reducing could be problematic. It'd be best to start with the volume size you need.
    – Tim
    Apr 18 '17 at 19:22

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