[EN] How I ended up paying US$154 for a single 60GB download from Amazon Glacier
The figure on the pricing page — “starting at $0.011 per gigabyte” — seems to indicate that usage pricing is used. But the model is actually closer to capacity-based pricing.
Glacier data retrievals are priced based on the peak hourly retrieval capacity used within a calendar month. You implicitly and retroactively “provision” this capacity for the entire month by submitting retrieval requests.
My single 60GB restore determined my data retrieval capacity, and hence price, for the month of January, with the following logic:
60.8GB retrieved over 4 hours = a peak retrieval rate of 15.2GB per hour
15.2GB/hour at $0.011/GB over the 744 hours in January = $124.40
Add 24% VAT for the total of $154.25.
Actual data transfer bandwith is extra.
Had I initiated the retrieval of a 3TB backup this way, the bill would have been $6,138.00 plus tax and AWS data transfer fees.
Q: How will I be charged when retrieving large amounts of data from Amazon Glacier?
You can retrieve up to 5% of your average monthly storage, pro-rated daily, for free each month. For example, if on a given day you have 75 TB of data stored in Amazon Glacier, you can retrieve up to 128 GB of data for free that day (75 terabytes x 5% / 30 days = 128 GB, assuming it is a 30 day month). In this example, 128 GB is your daily free retrieval allowance. Each month, you are only charged a Retrieval Fee if you exceed your daily retrieval allowance. Let's now look at how this Retrieval Fee - which is based on your monthly peak billable retrieval rate - is calculated.
Let’s assume you are storing 75 TB of data and you would like to retrieve 140 GB. The amount you pay is determined by how fast you retrieve the data. For example, you can request all the data at once and pay $21.60, or retrieve it evenly over eight hours, and pay $10.80. If you further spread your retrievals evenly over 28 hours, your retrievals would be free because you would be retrieving less than 128 GB per day. You can lower your billable retrieval rate and therefore reduce or eliminate your retrieval fees by spreading out your retrievals over longer periods of time.
Below we review how to calculate Retrieval Fees if you stored 75 TB and retrieved 140 GB in 4 hours, 8 hours, and 28 hours respectively.
First we calculate your peak retrieval rate. Your peak hourly retrieval rate each month is equal to the greatest amount of data you retrieve in any hour over the course of the month. If you initiate several retrieval jobs in the same hour, these are added together to determine your hourly retrieval rate. We always assume that a retrieval job completes in 4 hours for the purpose of calculating your peak retrieval rate. In this case your peak rate is 140 GB/4 hours, which equals 35 GB per hour.
Then we calculate your peak billable retrieval rate by subtracting the amount of data you get for free from your peak rate. To calculate your free data we look at your daily allowance and divide it by the number of hours in the day that you retrieved data. So in this case your free data is 128 GB /4 hours or 32 GB free per hour. This makes your billable retrieval rate 35 GB/hour – 32 GB per hour which equals 3 GB per hour.
To calculate how much you pay for the month we multiply your peak billable retrieval rate (3 GB per hour) by the retrieval fee ($0.01/GB) by the number of hours in a month (720). So in this instance you pay 3 GB/Hour * $0.01 * 720 hours, which equals $21.60 to retrieve 140 GB in 3-5 hours.
First we calculate your peak retrieval rate. Again, for the purpose of calculating your retrieval fee, we always assume retrievals complete in 4 hours. If you request 70GB of data at a time with an interval of at least 4 hours, your peak retrieval rate would then be 70GB / 4 hours = 17.50 GB per hour. (This assumes that your retrievals start and end in the same day).
Then we calculate your peak billable retrieval rate by subtracting the amount of data you get for free from your peak rate. To calculate your free data we look at your daily allowance and divide it by the number of hours in the day that you retrieved data. So in this case your free data is 128 GB /8 hours or 16 GB free per hour. This makes your billable retrieval rate 17.5 GB/hour – 16 GB per hour which equals 1.5 GB/hour. To calculate how much you pay for the month we multiply your peak hourly billable retrieval rate (1.5 GB/hour) by the retrieval fee ($0.01/GB) by the number of hours in a month (720). So in this instance you pay 1.5 GB/hour x $0.01 x 720 hours, which equals $10.80 to retrieve 40 GB.
If you spread your retrievals over 28 hours, you would no longer exceed your daily free retrieval allowance and would therefore not be charged a Retrieval Fee.
As you can see, you are able to significantly reduce, or eliminate, your retrieval fees when longer retrieval periods are suitable, as is often the case for archived data.