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Amazon S3 Glacier

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This is an old revision of this page, as edited by Cookingwithrye (talk | contribs) at 07:06, 5 March 2013 (more details about underlying storage + confusion thereof, better precision in summary section). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Amazon Glacier
Type of site
Online backup service
Available inEnglish
OwnerAmazon.com
URLaws.amazon.com/glacier/
CommercialYes
RegistrationRequired

Amazon Glacier is a low-cost online storage web service that provides reliable storage for data archiving and backup.[1]

Glacier is part of the Amazon Web Services suite of cloud computing services, and is designed for long-term storage of data that is infrequently accessed and for which retrieval latency times of 3 to 5 hours are acceptable. Storage costs are a consistent $0.01 per gigabyte per month, which is substantially cheaper than their own Simple Storage Service (S3) service.[2]

Amazon hopes this new service will move businesses from on-premises tape backup drives to cloud-based backup storage.[3]

Storage

ZDNet says, that according to private e-mail, Glacier runs on "inexpensive commodity hardware components", which are suggested to be high numbers of high-capacity low-cost hard discs.[3] It is possible that custom low-RPM hard drives are used in custom racks with proprietary logic.[4]


There is some confusion[5] amongst users that the underlying hardware used for Glacier storage is tape-based, owing to the fact that Amazon has positioned Glacier as a direct competitor to tape backup services (both on-premises and cloud-based), however all publicly available information (including communications with Amazon itself) appears to support the claim that Glacier is backed by inexpensive commodity hard drives and not tape. This confusion is exacerbated by the fact that Glacier experiences archive retrieval delays similar access delays to that of tape-based systems (3-5 hours before archives are available).

Cost

While an unlimited amount of data can be uploaded for storage, the pricing structure for downloading data (retrieval) is far more complex. Getting data out of Glacier is a two-step process. The first step is to retrieve the data from Glacier to regular S3 storage, subject to Glacier retrieval pricing. The next step is to actually download the data from the S3 storage. While Glacier advertises a free 5%/month allowance, this 5% is spread out evenly across the number of hours in a month for a 0.006944% free retrieval per hour (assuming a 30 day month). Exceeding the hourly allowance (aka peak hourly rate) at any time results in a peak retrieval overage charge that gets multiplied by the number of hours in a month.[6]

In the more practical terms, Glacier users need to break up any sizeable retrievals across the longest period of time practical to eliminate or minimize overage charges. Developers who are planning to implement Glacier support in their applications also need to implement a mechanism for spreading out data retrieval over a long period of time, and to be extremely careful with their testing: a simple mistake or misunderstanding can easily result in a massive bill. In one example, a user stored 15GB of data in Glacier, retrieved 693MB for testing, and ended up being charged for 126GB due to retrieval rate calculation.[7]

Data transfer between AWS regions is free up to 1 GB per month, after which a sliding scale fee starts at $0.12 per GB.[8] Data stored in Glacier but which is deleted after being stored for a period of less than 3 months incurs a charge of $0.03 per GB, a move designed to discourage the service's use in cases where Amazon's other storage offerings (e.g. S3) are more appropriate for real-time access.

Glacier is up to 90% cheaper than AWS S3 (PlanForCloud cost comparison), which in the past was the only way of archiving on the AWS cloud.

References

  1. ^ Mlot, Stephanie (August 21, 2012). "Amazon Launches Glacier Cloud Storage Service". PCMag.com. Ziff Davis, Inc. Retrieved 2012-08-21.
  2. ^ https://aws.amazon.com/s3/pricing/
  3. ^ a b Clark, Jack (August 21, 2012). "Amazon launches Glacier cloud storage, hopes enterprise will go cold on tape use". ZDNet. CBS Interactive. Retrieved 2012-08-21.
  4. ^ http://www.zdnet.com/could-the-tech-beneath-amazons-glacier-revolutionise-data-storage-7000003144/
  5. ^ http://www.extremetech.com/computing/134776-amazon-glacier-99-999999999-durability-long-term-storage-for-a-penny-a-gig
  6. ^ http://aws.amazon.com/glacier/faqs/#How_will_I_be_charged_when_retrieving_large_amounts_of_data_from_Amazon_Glacier
  7. ^ https://forums.aws.amazon.com/message.jspa?messageID=383204
  8. ^ http://aws.amazon.com/glacier/pricing/
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