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docs: document bookmarking + remove warning about replication lag

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refs #34
This commit is contained in:
Christian Schwarz
2017-12-28 13:24:25 +01:00
parent 03ba2bb7c8
commit 9a19615fd4
2 changed files with 14 additions and 9 deletions
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docs/configuration/jobs.rst
+9 -3
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@@ -54,6 +54,7 @@ Example: :sampleconf:`pullbackup/productionhost.yml`.
- Snapshotting Task (every ``interval``, |patient|)
- A snapshot of filesystems matched by ``filesystems`` is taken every ``interval`` with prefix ``snapshot_prefix``.
- A bookmark of that snapshot is created with the same name.
- The ``prune`` policy is triggered on filesystems matched by ``filesystems`` with snapshots matched by ``snapshot_prefix``.
- Serve Task
@@ -62,11 +63,13 @@ Example: :sampleconf:`pullbackup/productionhost.yml`.
A source job is the counterpart to a :ref:`job-pull`.
Note that the prune policy determines the maximum replication lag:
a pull job may stop replication due to link failure, misconfiguration or administrative action.
The source prune policy will eventually destroy the last common snapshot between source and pull job, requiring full replication.
Make sure you read the |prune| policy documentation.
Note that zrepl does not prune bookmarks due to the following reason:
a pull job may stop replication due to link failure, misconfiguration or administrative action.
The source prune policy will eventually destroy the last common snapshot between source and pull job.
Without bookmarks, the prune policy would need to perform full replication again.
With bookmarks, we can resume incremental replication, only losing the snapshots pruned since the outage.
.. _job-pull:
@@ -148,6 +151,7 @@ Example: :sampleconf:`localbackup/host1.yml`
#. Evaluate ``mapping`` for local filesystems, those with a *target filesystem* are called *mapped filesystems*.
#. Snapshot *mapped filesystems* with ``snapshot_prefix``.
#. Bookmark the snapshot created above.
#. Replicate *mapped filesystems* to their respective *target filesystems*:
#. Only snapshots with prefix ``snapshot_prefix`` are replicated.
@@ -159,6 +163,8 @@ Example: :sampleconf:`localbackup/host1.yml`
#. The ``prune_rhs`` policy is triggered for all *target filesystems*
A local job is combination of source & pull job executed on the same machine.
Note that while snapshots are pruned, bookmarks are not pruned and kept around forever.
Refer to the comments on :ref:`source job <job-source>` for the reasoning behind this.
Terminology
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