You can configure the replication pairs for different patterns of replication through the Oracle MaxRep for SAN protections plan options.
Available replication options include the number of pairs to resynchronize simultaneously and compressed data transfer from the primary
Oracle MaxRep Replication Engine to the secondary
Replication Engine. These options are described in the following list.
Note: The synchronous or asynchronous configuration of the Replication Engines determines the available replication options. Not all options are available for all configurations.
- Secure data transfer from Primary Process Service to Secondary Process Service
Encrypts data before transferring it to a process service
Replication Engine.
Important: Because encrypted transmissions can have performance penalties when compared to unencrypted transmissions, we do not recommend encryption in cases where the WAN link between the source and target storage is a dedicated secure WAN. Enable encryption if you are using a public common carrier for WAN attached asynchronous replication.
- Batch Resync
Specifies the number of replication pairs in a protection plan that are resynchronized simultaneously.
For example, if the batch resynchronization value is 2 and you have four pairs in a protection plan, resynchronization starts for two of the pairs while the other two pairs remain in a Queued state. After the pair reaches differential sync, the next pair starts step 1 of the resynchronization process. The recovery point originates only from the resynchronization start time, not the pair configuration time.
- Automatic Resync Options
Specifies whether to correct any replication data inconsistencies automatically. When an inconsistency occurs, a warning message displays on the Alerts and Notifications panel of the Monitor page and the pair is marked as resynchronized required.
When you enable the
Automatic Resync Option and set the
Resync required option to
Yes, the system waits for a specified period of time (by default it is 30 minutes) before performing a forced resynchronization within the
Start between hours time frame. This wait ensures data consistency and minimizes manual intervention.
Note: When the Automatic Resync Option is not configured for a protection plan, manual intervention will be required if resynchronization is required.
- Sync Options
- Sync options define how the Replication Engines ensure that the data on the source and target LUNs initially synchronize with one another. If the source and target LUNs do not synchronize, these LUNs can return to a synchronized state in the future.
- Fast Sync
Performs a faster resynchronization than the basic resynchronization at the cost of using more CPU resources on the primary server.
Note: The Fast Sync option is only available for asynchronous configurations.
The Fast Sync option specifies that Oracle MaxRep reads a data block on the source LUN and calculates the unmatched data in a hash. The system then reads the same blocks of data on the target LUN and calculates a corresponding hash. The hash is transferred over the network between the source and target Replication Engines.
If the data hashes match, no data is transferred to the target LUN. When the data hashes do not match, the data is transferred over the network between the Replication Engines.
This process minimizes the network traffic between the systems and can greatly reduce resynchronization times because only differing data are transmitted between the Replication Engines.
- Direct Copy
Copies data directly between source and target
LUNs without requiring verification.
Note: The Direct Copy option is only available for synchronous configurations.
This option is available when both source and target LUNs are accessible from the same Replication Engine or clustered high availability pair of Replication Engines. A direct copy occurs only in synchronous replication configurations.
- Compression
-
Defines whether compression is used for data transmitted across the WAN. Because compression can consume valuable system resources on the Replication Engines, Oracle recommends that you use the Replication Engines only in asynchronous replication environments across a limited bandwidth WAN. For sizing considerations, contact Oracle Customer Support.
Data compression effectiveness varies widely depending on the type of data being compressed. Typically, you can plan on the compression ratios for various data types as defined in the following table.
Table 1 Compression ratios by file type| File type |
Compression ratio |
|---|
| General files |
2:1 |
| Database |
4:1 |
| Graphics and media |
1:1 |
| Messaging, such as email |
4:1 |
- Resync File Threshold
-
Specifies the folder size of the threshold resynchronization cache. When the resynchronization cache folder exceeds this size, the data transfer rate between the source and target
LUNs is throttled. The default value is 16 GB.
Note: Setting the Resync file threshold too high might have a negative impact on available system resources on the Replication Engines. Setting the threshold too low might result in increased recovery point objective (RPO) times during high data loads.
- Differential File Threshold
Specifies the folder size of the threshold differential synchronization cache. When the differential cache folder exceeds this size, the data transfer rate between the source and target
LUNs is throttled. The default value is 65 GB for all
LUNs except for
LUNs with high data change rates.
Note: Do not set the Differential File Threshold option unless directed by Oracle Customer Support.
- RPO Threshold
Specifies the threshold recovery point objective (RPO) in minutes. The RPO represents the maximum amount of time that the replication pair is allowed to fall behind synchronous mode. If RPO increases beyond this limit, the
Oracle MaxRep system sends a message to the GUI interface. This setting has no affect on replication.
Note: Do not set the RPO Threshold option unless directed by Oracle Customer Support.