Custom metadata collisions

A custom metadata collision occurs when:

For an HCP namespace, these events occur in the order shown:

1.One of these changes occurs:

An annotation is added with the same name to a given object on both systems involved in a replication link, but the annotation has different content on the two systems.

The addition of an annotation to a given object on only one of the systems does not result in a custom metadata collision if the object does not have an annotation with the same name on the other system. In this case, the new annotation is replicated without conflict.

Different changes are made to the content of a given annotation for a given object on each of the two systems involved in a replication link.

A change is made to the content of a given annotation for a given object on one of the systems involved in a replication link, and the same annotation is deleted on the other system involved in the link.

2.The change made on one of the systems is replicated to the other system.

For a default-namespace directory, these events occur in the order shown:

1.One of these changes occurs:

Custom metadata is added to a given object on both systems involved in a replication link, but the added custom metadata is different on the two systems.

The addition of custom metadata to an object on only one of the systems involved in a replication link does not result in a custom metadata collision. Instead, the new custom metadata is replicated from that system to the other system involved in the link without conflict.

The custom metadata for a given object is replaced on both systems involved in a replication link, but the replacement custom metadata is different on the two systems.

The custom metadata for a given object is replaced on one of the systems involved in a replication link, and the same custom metadata is deleted on the other system involved in the link.

2.The change made on one of the systems is replicated to the other system.

If a collision occurs when a custom metadata change for a given object is replicated from one system (system A) involved in a replication link to the other system (system B) involved in the link:

If the last change on system A is more recent than the last change on system B, HCP applies the change from system A to the custom metadata on system B

If the last change on system B is more recent than the last change on system A, HCP does not change the custom metadata on system B

Here are some examples of how HCP handles collisions when custom metadata changes for a given object are replicated from one system (system A) involved in a replication link to the other system (system B) involved in the link.

Example 1

In an HCP namespace, the object starts out with annotations named a1 and a2 on both system A and system B.

The table below shows a sequence of events in which the annotations for the object are changed and the changes are then replicated.

Sequence Event
1

On system B, a client changes the content of a1.

2

On system A, a client makes a different change to the content of a1.

3

On system A, a client adds annotation a3 to the object.

4

On system B, a client adds annotation a3 with different content from the a3 added on system A.

5

The changes on system A are replicated to system B. The resulting annotations for the object on system B are:

a1 with the changed content from system A
a2 (unchanged)
a3 with the content added on system B

6

The changes on system B are replicated to system A. The resulting annotations for the object on system A are:

a1 with the changed content from system A
a2 (unchanged)
a3 with the content added on system B

Example 2

In an HCP namespace, the object starts out with the annotations named a1, a2, and a3 on both system A and system B.

The table below shows a sequence of events in which the annotations for the object are changed and the changes are then replicated.

Sequence Event
1

On system B, a client changes the content of a1.

2

On system A, a client deletes a1.

3

On system A, a client changes the content of a2.

4

On system B, a client changes the content of a2.

5

On system A, a client deletes a3.

6

On system B, a client changes the content of a3.

7

The changes on system A are replicated to system B. The resulting annotations for the object on system B are:

a2 with the changed content from system B
a3 with the changed content from system B

8

The changes on system B are replicated to system A, the resulting annotations for the object on system A are:

a2 with the changed content from system B
a3 with the changed content from system B

Example 3

In a default-namespace directory, the object starts out with same custom metadata on system A and system B.

The table below shows a sequence of events in which the custom metadata for the object is changed and the change is then replicated.

Sequence Event
1

On system B, a client replaces the custom metadata for the object with new custom metadata.

2

On system A, a client replaces the custom metadata for the object with different custom metadata from the custom metadata used on system B.

3

The change on system A is replicated to system B. The resulting custom metadata for the object on system B is the new custom metadata from system A.

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