zrepl/docs/configuration/conflict_resolution.rst
Christian Schwarz 2642c64303 make initial replication policy configurable (most_recent, all, fail)
Config:

```
- type: push
  ...
  conflict_resolution:
    initial_replication: most_recent | all | fali
```

The ``initial_replication`` option determines which snapshots zrepl
replicates if the filesystem has not been replicated before.
If ``most_recent`` (the default), the initial replication will only
transfer the most recent snapshot, while ignoring previous snapshots.
If all snapshots should be replicated, specify ``all``.
Use ``fail`` to make replication of the filesystem fail in case
there is no corresponding fileystem on the receiver.

Code-Level Changes, apart from the obvious:
- Rework IncrementalPath()'s return signature.
  Now returns an error for initial replications as well.
- Rename & rework it's consumer, resolveConflict().

Co-authored-by: Graham Christensen <graham@grahamc.com>

Fixes https://github.com/zrepl/zrepl/issues/550
Fixes https://github.com/zrepl/zrepl/issues/187
Closes https://github.com/zrepl/zrepl/pull/592
2022-06-26 14:36:59 +02:00

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.. include:: ../global.rst.inc
Conflict Resolution Options
===========================
::
jobs:
- type: push
filesystems: ...
conflict_resolution:
initial_replication: most_recent | all | fail # default: most_recent
...
.. _conflict_resolution-initial_replication-option-send_all_snapshots:
``initial_replication`` option
------------------------------
The ``initial_replication`` option determines how many snapshots zrepl replicates if the filesystem has not been replicated before.
If ``most_recent`` (the default), the initial replication will only transfer the most recent snapshot, while ignoring previous snapshots.
If all snapshots should be replicated, specify ``all``.
Use ``fail`` to make replication of the filesystem fail in case there is no corresponding fileystem on the receiver.
For example, suppose there are snapshosts ``tank@1``, ``tank@2``, ``tank@3`` on a sender.
Then ``most_recent`` will replicate just ``@3``, but ``all`` will replicate ``@1``, ``@2``, and ``@3``.
If initial replication is interrupted, and there is at least one (maybe partial) snapshot on the receiver, zrepl will always resume in **incremental mode**.
And that is regardless of where the initial replication was interrupted.
For example, if ``initial_replication: all`` and the transfer of ``@1`` is interrupted, zrepl would retry/resume at ``@1``.
And even if the user changes the config to ``initial_replication: most_recent`` before resuming, **incremental mode** will still resume at ``@1``.