Increase file reliability against group failure #2059

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markberger · 2013-08-17T22:08:51Z

markberger commented

2013-08-17 22:08:51 +00:00

Servers of happiness improves share distribution and guarantees a file can be recovered for up to h - k node failures. However, if a group of nodes fail, servers of happiness makes no guarantees. If I lose all the machines in my house, I have no way of knowing whether my other nodes have enough shares to reconstruct all my data.

One way of fixing this is to group a maximum of h - k nodes in a single location, but I think that solution is silly because I might not want to increase my n or lower my h to meet the requirement. Instead, I should be able to organize storage nodes into failure groups and guarantee that a subset of those groups will be able reconstruct every file. Given a set of groups with g cardinality, any subset with a cardinality of g - 1 must have k shares.

This is somewhat related to #467, but I think this ticket serves a different purpose.

Servers of happiness improves share distribution and guarantees a file can be recovered for up to h - k node failures. However, if a group of nodes fail, servers of happiness makes no guarantees. If I lose all the machines in my house, I have no way of knowing whether my other nodes have enough shares to reconstruct all my data. One way of fixing this is to group a maximum of h - k nodes in a single location, but I think that solution is silly because I might not want to increase my n or lower my h to meet the requirement. Instead, I should be able to organize storage nodes into failure groups and guarantee that a subset of those groups will be able reconstruct every file. Given a set of groups with g cardinality, any subset with a cardinality of g - 1 must have k shares. This is somewhat related to #467, but I think this ticket serves a different purpose.

markberger added the

labels 2013-08-17 22:08:51 +00:00

markberger added this to the undecided milestone 2013-08-17 22:08:51 +00:00

markberger commented

2013-08-19 12:49:02 +00:00

This feature should be disabled by default because new users should have to change as few options as possible to start using tahoe.

PRabahy commented

2013-08-19 20:41:51 +00:00

Looks related to/duplicate of #1838 to me.

zooko commented

2013-08-21 03:08:13 +00:00

I agree that this is a dup of #1838. As often happens, the text in this dup should be read by readers of the other ticket, so I'll post a comment there urging them to do so. Oh, by the way, please read #573, which was another dup and also had a lot of useful detail.

zooko added the

duplicate

label 2013-08-21 03:08:13 +00:00

zooko closed this issue

2013-08-21 03:08:13 +00:00

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