Changes between Version 16 and Version 17 of FAQ
- Timestamp:
- 2010-03-08T08:08:12Z (15 years ago)
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FAQ
v16 v17 7 7 Q: "Erasure-coding"? What's that? 8 8 9 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. 9 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. (This technique is also known as "forward error correction" and as an "information dispersal algorithm".) 10 10 11 11 Q: Is there a way to disable the encryption phase and just use the encoding on the actual content? Won't that save a lot of CPU cycles?
