servers-of-happiness is too conservative when K = 1 #1293

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tahoe-lafs · 2011-01-05T03:27:55Z

davidsarah commented

2011-01-05 03:27:55 +00:00

When K = 1, any single share is sufficient to reconstruct the file. However, the servers-of-happiness code will still require that there are H servers with unique share numbers. It should not care about the share numbers.

(We knew of examples with small K where the maximum matching definition of servers-of-happiness was conservative relative to the original definition, e.g. /tahoe-lafs/trac-2024-07-25/issues/5840#comment:198. However, for K > 1 it is more space-efficient to use the maximum matching definition. For K = 1 it is not.)

When K = 1, any single share is sufficient to reconstruct the file. However, the servers-of-happiness code will still require that there are H servers with unique share numbers. It should not care about the share numbers. (We knew of examples with small K where the maximum matching definition of servers-of-happiness was conservative relative to the original definition, e.g. [/tahoe-lafs/trac-2024-07-25/issues/5840](/tahoe-lafs/trac-2024-07-25/issues/5840)#comment:198. However, for K > 1 it is more space-efficient to use the maximum matching definition. For K = 1 it is not.)

tahoe-lafs added the

labels 2011-01-05 03:27:55 +00:00

tahoe-lafs added this to the 1.9.0 milestone 2011-01-05 03:27:55 +00:00

tahoe-lafs modified the milestone from 1.9.0 to 1.8.2

2011-01-06 00:32:21 +00:00

zooko commented

2011-01-18 08:25:28 +00:00

I think we're out of time for 1.8.2. (Apologies if you're actually still intending to do this for 1.8.2.)

zooko modified the milestone from 1.8.2 to 1.9.0

2011-01-18 08:25:28 +00:00

davidsarah commented

2011-07-24 22:42:30 +00:00

It makes sense to fix this at the same time as Kevan's changes to share placement behaviour in #1382, which will not be in 1.9.

tahoe-lafs modified the milestone from 1.9.0 to 1.10.0

2011-07-24 22:42:30 +00:00

markberger commented

2013-08-28 15:19:13 +00:00

For example, if we have a share distribution like this:

Server A: [1]
Server B: [1]
Server C: [1]

with k = 1 and h = 3, the placement will be considered unhealthy even though we don't care about the share numbers because any single share is sufficient to reconstruct the file.

For example, if we have a share distribution like this: * Server A: `[1]` * Server B: `[1]` * Server C: `[1]` with k = 1 and h = 3, the placement will be considered unhealthy even though we don't care about the share numbers because any single share is sufficient to reconstruct the file.

tahoe-lafs modified the milestone from 1.11.0 to 1.12.0

2013-08-28 15:22:48 +00:00

warner commented

2016-03-22 05:02:25 +00:00

Milestone renamed

warner modified the milestone from 1.12.0 to 1.13.0

2016-03-22 05:02:25 +00:00

warner commented

2016-06-28 18:17:14 +00:00

renaming milestone

warner modified the milestone from 1.13.0 to 1.14.0

2016-06-28 18:17:14 +00:00