103 lines
5.3 KiB
Markdown
103 lines
5.3 KiB
Markdown
---
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title: Content-Addressable Storage
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TARGET DECK: Obsidian::STEM
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FILE TAGS: fs::cas
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tags:
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- cas
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- fs
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---
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## Overview
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CAS (**c**ontent-**a**ddressed **s**torage) refers to storage that allows retrieval based on content (as opposed to name or location). Usually the contents of a file are passed through a cryptographic hash function to generate a key that can be used for subsequent retrieval.
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%%ANKI
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Basic
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What is content-addressed storage?
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Back: A method for storing information such that it can be retrieved based on its content.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255543-->
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END%%
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%%ANKI
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Basic
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What is considered the "opposite" of content-addressed storage?
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Back: Location-addressed storage.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255547-->
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END%%
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%%ANKI
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Basic
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What is CAS an acronym for?
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Back: **C**ontent-**a**ddressed **s**torage.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255550-->
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END%%
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%%ANKI
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Cloze
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{1:Content}-addressed is to {2:URNs} whereas {2:location}-addressed is to {1:URLs}.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255553-->
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END%%
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%%ANKI
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Basic
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Interpreted as a key-value store, what is a "key" in a CAS system?
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Back: The digest produced when running content through a cryptographic hash function.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255556-->
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END%%
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%%ANKI
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Basic
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Interpreted as a key-value store, what is a "value" in a CAS system?
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Back: The actual content being stored.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255559-->
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END%%
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%%ANKI
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Basic
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In the context of CAS, what is a "content address"?
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Back: A digest produced when running content through a cryptographic hash function.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255562-->
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END%%
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%%ANKI
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Cloze
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Content addresses are an alternative to {location} addresses found in traditional filesystems.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255565-->
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END%%
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%%ANKI
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Basic
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Why are CAS systems sometimes called "fixed content storage"?
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Back: CAS is normally used for files that are not frequently edited.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255567-->
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END%%
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%%ANKI
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Basic
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How is it CAS systems ensure file uniqueness?
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Back: An attempt to store an already stored file will generate the same key as before.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255570-->
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END%%
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%%ANKI
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Basic
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How is it CAS systems ensure file's remain unchanged?
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Back: A file's key will always be the same provided the content has not changed.
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Reference: “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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<!--ID: 1709177255573-->
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END%%
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## Bibliography
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* “Content-Addressable Storage,” in _Wikipedia_, February 27, 2024, [https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681](https://en.wikipedia.org/w/index.php?title=Content-addressable_storage&oldid=1210669681).
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* Scott Chacon, _Pro Git_, Second edition, The Expert’s Voice in Software Development (New York, NY: Apress, 2014). |