openstack/swift
Code Issues Proposed changes

Merge "Fix EC documentation of .durable quorum"

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Jenkins 2015-10-08 20:53:58 +00:00 committed by Gerrit Code Review
commit e2498083b4
1 changed files with 5 additions and 6 deletions
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11
doc/source/overview_erasure_code.rst
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@ -422,11 +422,10 @@ presence of a `ts.durable` file means, to the object server, `there is a set
of ts.data files that are durable at timestamp ts`.
For the second phase of the conversation the proxy requires a quorum of
`ec_nparity + 1` successful commits on storage nodes. This ensures that for
as long there are sufficient (i.e. `ec_ndata`) fragment archives to reconstruct
the object then there will be a `.durable` file on at least one storage node.
The reconstructor ensures that `.durable` files are replicated on storage nodes
where they may be missing.
`ec_ndata + 1` successful commits on storage nodes. This ensures that there are
sufficient committed fragment archives for the object to be reconstructed even
if one becomes unavailable. The reconstructor ensures that `.durable` files are
replicated on storage nodes where they may be missing.
Note that the completion of the commit phase of the conversation
is also a signal for the object server to go ahead and immediately delete older
@ -445,7 +444,7 @@ The basic flow looks like this:
* Upon receipt of commit message, object servers store a 0-byte data file as
`<timestamp>.durable` indicating successful PUT, and send a final response to
the proxy server.
* The proxy waits for `ec_nparity + 1` object servers to respond with a
* The proxy waits for `ec_ndata + 1` object servers to respond with a
success (2xx) status before responding to the client with a successful
status.