What is content-addressable storage (CAS), and how does it work? |
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| 13 Jun 2008 | Terri McClure |
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CAS is a way of storing information that can be retrieved based on its content, instead of its storage location. It's typically used for long-term storage and retrieval of fixed content, like documents stored with compliance for government regulations, or medical records like x-rays and MRIs. In other words, when you think about storage, everything has an address. For conventional file systems, it's a name and a location in a hierarchy of directories.
A CAS system uses the content itself as an address through a unique identifier, typically using a hashing algorithm performed against the content. That makes the content address unique. No two pieces of content have the same address unless the content is exactly the same.
Using content-addressing models provides three main benefits:
- The need for applications to understand the physical location of information is eliminated.
- A content address acts a digital fingerprint, which can be used for irrefutable authenticity during a legal or regulatory investigation.
- Digital fingerprints are used to identify and eliminate duplicate records, such as emails with attachments, which ultimately reduce archive capacity requirements.
Check out the entire CAS FAQ.
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