[tahoe-dev] the first three FAQs

Zooko Wilcox-O'Hearn zooko at zooko.com
Mon Oct 19 23:08:39 UTC 2009

I just created the FAQ page on the wiki, which up until now was an  
empty page that said "Click here to create this page".  If you can  
think of any other Frequently Asked Questions, please add them to  
this page:


Q: What is special about Tahoe-LAFS? Why should anyone care about it  
instead of other distributed storage systems?
A: Tahoe-LAFS is the first Free Software/Open Source storage  
technology which offers provider-independent security. Provider- 
independent security means that the integrity and confidentiality of  
your files is guaranteed by mathematics computed on the client side,  
and is independent of the servers, which may be owned and operated by  
someone else. To learn more, read our one-page explanation.

Q: Oh, so I should be interested in Tahoe-LAFS only if I'm working on  
some sort of high-security project?

A: No, no! Unlike most systems Tahoe-LAFS doesn't require you to  
manage an added layer of hassle in order to gain security. Instead  
the security properties are baked into the system in such a way that  
you usually don't even notice that they are there. Even if you don't  
care about protecting your files from someone spying on them or  
corrupting them, you might still like to use Tahoe-LAFS because it is  
an extremely robust and efficient "cloud storage" system in which  
your files are erasure-coded and distributed across separate servers.

Q: "Erasure-coding"? What's that?

A: You know how with RAID-5 you can lose any one drive and still  
recover? And there is also something called RAID-6 where you can lose  
any two drives and still recover. Erasure coding is the  
generalization of this pattern: you get to configure it for how many  
drives you could lose and still recover. Tahoe-LAFS is typically  
configured to upload each file to 10 different drives, where you can  
lose any 7 of them and still recover the entire file. This gives  
radically better reliability than typical RAID setups, at a cost of  
only 3.3 times the storage space that a single copy takes.

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