-The Arvados distributed file system is called *Keep*. Keep is a content-addressable file system. This means that files are managed using special unique identifiers derived from the _contents_ of the file, rather than human-assigned file names (specifically, the md5 hash). This has a number of advantages:
-* Files can be stored and replicated across a cluster of servers without requiring a central name server.
-* Both the server and client systematically validate data integrity because the checksum is built into the identifier.
-* Data duplication is minimized—two files with the same contents will have in the same identifier, and will not be stored twice.
-* It avoids data race conditions, since an identifier always points to the same data.
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-h1. Putting Data into Keep
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-We will start by downloading a freely available VCF file from "Personal Genome Project (PGP)":http://www.personalgenomes.org subject "hu599905":https://my.personalgenomes.org/profile/hu599905 to a staging directory on the VM, and adding it to Keep. In the following commands, replace *@you@* with your login name.
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-First, log into your Arvados VM and set up the staging area:
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-notextile. <pre><code>~$ <span class="userinput">mkdir /scratch/<b>you</b></span></code></pre>
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-Next, download the file: