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PBM-1450 Added a note how node priorities interfere with incrementalb… #233

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PBM-1450 Added a note how node priorities interfere with incrementalb… #233

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PBM-1450 Added a note how node priorities interfere with incrementalb…
nastena1606 Nov 26, 2024
db75a5a
Updated recommendation for prio definition
nastena1606 Dec 9, 2024
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8 changes: 6 additions & 2 deletions docs/features/incremental-backup.md
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Expand Up @@ -25,9 +25,13 @@

## Implementation specifics

Percona Backup for MongoDB tracks the backup history only on the node where the base incremental backup was taken. This means that subsequent incremental backups must always be run on that very node. To make this happen, Percona Backup for MongoDB tries to schedule backups on that same node.
1. Percona Backup for MongoDB tracks the backup history only on the node where the base incremental backup was taken. This means that subsequent incremental backups must always be run on that very node. To make this happen, Percona Backup for MongoDB tries to schedule backups on that same node.

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{"message": "[Google.Passive] In general, use active voice instead of passive voice ('was taken').", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 28, "column": 108}}}, "severity": "INFO"}

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{"message": "[Google.Passive] In general, use active voice instead of passive voice ('be run').", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 28, "column": 178}}}, "severity": "INFO"}

If the node with the base incremental backup is down or unavailable, you must start the incremental backup chain anew on another node.
If the node with the base incremental backup is down or unavailable, you must start the incremental backup chain anew on another node.

2. Adjusting node priorities for backup interferes with the default behaviour described above. If only a subset of nodes is listed for the priority, the remaining nodes receive the default priority 1 and it may happen that the incremental backup is taken not from the node where the base backup was taken.

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{"message": "[Google.WordList] Use 'preceding' instead of 'above'.", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 32, "column": 89}}}, "severity": "WARNING"}

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[Google.Passive] In general, use active voice instead of passive voice ('is listed').
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{"message": "[Google.Passive] In general, use active voice instead of passive voice ('is listed').", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 32, "column": 122}}}, "severity": "INFO"}

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[Google.Passive] In general, use active voice instead of passive voice ('is taken').
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{"message": "[Google.Passive] In general, use active voice instead of passive voice ('is taken').", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 32, "column": 247}}}, "severity": "INFO"}

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[Google.Passive] In general, use active voice instead of passive voice ('was taken').
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{"message": "[Google.Passive] In general, use active voice instead of passive voice ('was taken').", "location": {"path": "docs/features/incremental-backup.md", "range": {"start": {"line": 32, "column": 296}}}, "severity": "INFO"}
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To avoid this, make sure to either list all nodes in the priority list or least one node from every replica set .

[Make a backup](../usage/start-backup.md){ .md-button .md-button }
[Restore a backup](../usage/restore.md){ .md-button .md-button }
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5 changes: 5 additions & 0 deletions docs/usage/start-backup.md
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Expand Up @@ -199,6 +199,11 @@ If you haven’t listed any nodes for the `priority` option in the config, the n

As soon as you adjust node priorities in the configuration file, it is assumed that you take manual control over them. The default rule to prefer secondary nodes over primary stops working.

Adjusting node priority interferes the default flow for incremental backups, where PBM tries to schedule the incremental backup on happen on the same node that made the base backup. If you list only a subset of nodes in the priority list, the remaining nodes receive the default priority 1.0. This may result in the incremental backup being taken from a node that didn't make the base backup.

To workaround it, list either all nodes or at least a single node from every replica set in the priorities list.


This ability to adjust node priority helps you manage your backup strategy by selecting specific nodes or nodes from preferred data centers. In geographically distributed infrastructures, you can reduce network latency by making backups from nodes in geographically closest locations.

## Next steps
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