A system metadata collision occurs when these events occur in the order shown:
1.Different changes are made to the system metadata for a given object on each of two systems in a replication topology.
2.The changed system metadata on one of the systems is replicated to the other system.
For example, suppose a user on one system changes the shred setting for an object while a user on the other system changes the index setting for the same object. When the object on either system is replicated to the other system, a system metadata collision occurs.
If a collision occurs when changed system metadata for a given object is replicated from one system (system A) in a replication topology to another system (system B) in the topology:
•For changed system metadata other than the retention setting and hold status:
oIf the last change made on system A is more recent than the last change made on system B, HCP changes the system metadata on system B to match the system metadata on system A.
oIf the last change on system B is more recent than the last change on system A, HCP does not change the system metadata on system B.
•For a changed retention setting:
oIf the retention setting on system A specifies a longer retention period than does the retention setting on system B, HCP changes the retention setting on system B to match the retention setting on system A.
oIf the retention setting on system B specifies a longer retention period than does the retention setting on system A, HCP does not change the retention setting on system B.
•For a changed hold status:
oIf the object is on hold on system A but not on system B, HCP places the object on hold on system B.
oIf the object is on hold on system B but not on system A, HCP leaves the object on hold on system B.
Here are some examples of how HCP handles collisions when changed system metadata for a given object is replicated from one system (system A) in a replication topology to another system (system B) in the topology.
Example 1
The object starts out on both system A and system B with these system metadata settings:
Shred: false
Index: false
The table below shows a sequence of events in which the system metadata for the object is changed and the changes are then replicated.
Sequence |
Event |
---|---|
1 |
On system A, a client changes the shred setting to true. |
2 |
On system B, a client changes the index setting to true. |
3 |
The changes on system A are replicated to system B. The resulting settings for the object on system B are: Shred: false |
Example 2
The object starts out on both system A and system B with these system metadata settings:
Retention: Initial Unspecified
Shred: false
Index: false
The table below shows a sequence of events in which the system metadata for the object is changed and the changes are then replicated.
Sequence |
Event |
---|---|
1 |
On system A, a client changes the retention setting to Deletion Prohibited. |
2 |
On system B, a client changes the retention setting to Deletion Allowed. |
3 |
On system B, a client changes the index setting to true. |
4 |
On system A, a client changes the shred setting to true. |
5 |
The changes on system A are replicated to system B. The resulting settings for the object on system B are: Retention: Deletion Prohibited |
Example 3
The object starts out on both system A and system B with these system metadata settings:
Retention: Initial Unspecified
Hold: true
Shred: false
Index: false
The table below shows a sequence of events in which the system metadata for the object is changed and the changes are then replicated.
Sequence |
Event |
---|---|
1 |
On system A, a client changes the retention setting to Deletion Allowed. |
2 |
On system B, a client changes the retention setting to Deletion Prohibited. |
3 |
On system B, a client changes the index setting to true. |
4 |
On system A, a client changes the shred setting to true. |
5 |
On system A, a client releases the object from hold. |
6 |
The changes on system A are replicated to system B. The resulting settings for the object on system B are: Retention: Deletion Prohibited |
7 |
The changes on system B are replicated to system A. The resulting settings for the object on system A are: Retention: Deletion Prohibited |
© 2015, 2020 Hitachi Vantara LLC. All rights reserved.