| Windows | Unix | How To |
A Replication Pair is used to map a designated set of data on a source computer to a location on a destination computer. This monitors change on the source and replicate the changes to the destination computer.
The activity of Replication Pairs can be controlled individually, or when acting from the Replication Set level, multiple Replication Pairs are controlled at the same time. Activities related to a Replication Pair include:
For step-by-step instructions, see Add a Replication Pair
You can optionally specify a Common Base Folder, so that all destination paths for all Replication Pairs in the Replication Set will be created in the same folder on the destination host. This can be useful when you are adding multiple Replication Pairs at the same time, as in the case of replicating application data. For example:
If you specify C:\replication\dest as the base directory, your Replication Pairs might use the following as their destination directories:
C:\replication\dest\source_path_1\
C:\replication\dest\source_path_2\
C:\replication\dest\source_path_3\
If the source_path_1 is specified as C:\rep_pair_1 then the Replication Pair will use C:\replication\dest\C\rep_pair_1 as its destination directory.
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Certain Replication Pair combinations are not possible, or are only possible using different Replication Sets. The following table highlights the most common such cases, without enabling chaining for replication option in a control panel:
| Type of Combination or Conflict | Same Replication Set | Different Replication Set |
Examples Note that (A), (B), (C) in the examples represent different computers |
Notes |
| Exact same destination path | No | No | (A) D:\test
=> (B) E:\test (A) F:\test => (B) E:\test |
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| Child/parent destination paths | No | No | (A) D:\test
=> (B) E:\test (C) F:\test => (B) E:\test\test1 - - - - - - (A) D:\test => (B) E:\test (C) F:\ => (B) E:\ |
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| Source path same as destination (volumes are on different computers) | N/A | Yes | (A) D:\test
=> (B) D:\test (C) D:\test => (B) E:\test |
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| Same destination path on multiple computers | N/A | Yes | (A) D:\test
=> (B) D:\test (A) D:\test => (C) D:\test |
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| Same destination volume, different folders | Yes | Yes | (A) D:\test
=> (B) D:\test (C) E:\data => (B) D:\test1 |
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| Same source path in multiple pairs | No | Yes | (A) D:\test
=> (B) D:\test (A) D:\test => (C) E:\test |
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| Source parent folder already used (Nested mount point is not supported.) |
Yes | Yes | Existing: (A) D:\ => (B) D:\ New: (A) D:\data => (B) E:\data |
The new pair will change to the parent path. |
| Source child folder already used | No | No | Existing: (A) D:\data => (B) E:\data New: (A) D:\ => (B) D:\ |
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| Destination parent folder already used | No | No | Existing: (A) E:\src => (B) G:\des New: (B) G:\des => (C) I:\ (B) G:\ => (C) I:\des1 (B) G:\data => (C) H:\test (B) G:\des\test => (C) I: |
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You can enable chaining for replication to use destination paths as a source
for replication pairs. For step-by-step instructions to enable chaining, see
Enable Chaining for Replication. For chaining, replication pair source and destination paths can be configured as follows: (A) E:\test => (B) G:\test (B) G:\test => (C) H:\data (C) H:\data => (D) I:\test Ensure that your destination data is not replicated back to any volume that is being used as a source as this may cause an endless loop. For example: (A) E:\test => (B) G:\test (B) G:\test => (C) H:\data (C) H:\data => (D) I:\test (D) I:\test => (A) E:\test or E:\ (OR) (A) D:\test => (B) G:\data (A) F:\test1 => (B) H:\data1 Note that when you create a new replication pair(s) as below then it will from an endless loop. (B) G:\data => (A) F:\test1 (B) H:\data1 => (A) D:\test Here (A), (B), (C), (D) are different computers |
When creating a Replication Pair, and selecting the source and destination paths for replication, consider the following:
| Attempting to use CDR to protect the system volume of a Windows computer is strongly discouraged. Due to the normally high rate of I/O on such a volume (e.g., the C: drive), it would prove very difficult to create a snapshot of it, since a sufficient period of no disk activity is required in order to create the snapshot. Similarly, a system volume is an inappropriate choice as a destination for data replication, and is also strongly discouraged. |
For instance, Replication Set 1 could have a Replication Pair configured as follows:
Replication Set 2 could have a Replication Pair configured as follows:
When selecting a destination folder for a Replication Pair, ensure that the selected path does not contain any data as the existing data will be pruned during Orphan File processing.