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Manual Chapter: Deduplication
Manual Chapter
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What is symmetric data deduplication?

WAN Optimization Manager (WOM) uses symmetric data deduplication to reduce the amount of bandwidth consumed across a WAN link for repeated data transfers. This feature is available only with a WOM® license.

With data deduplication, the system performs pattern matching on the transmitted WAN data, rather than caching. If any part of the transmitted data has already been sent, BIG-IP® WOM replaces the previously transmitted data with references. As data flows through the pair, each WOM records the byte patterns and builds a synchronized dictionary. If an identical pattern of bytes traverses the WAN more than once, the BIG-IP WOM closest to the sender replaces the byte pattern with a reference to it, compressing the data. When the reference reaches the other side of the WAN, the remote BIG-IP WOM replaces the reference with the data, restoring the data to its original format.

Which codec do I choose?

Symmetric data deduplication (SDD) offers two versions, called codecs. SDD v3 is appropriate for most WOM installations, particularly in large networks, such as hub and spoke, or mesh deployments. SSD v2 is an alternative for installations with fewer than eight high-speed links, such as for data replication between data centers.

For deduplication to occur, the same codec must be selected on both iSession endpoints. If the selected codecs do not match, deduplication does not occur, although other WOM features, such as compression, still take place.

Enabling symmetric data deduplication

Ensure that you have licensed and provisioned WAN Optimization Manager™ (WOM) on the BIG-IP® system.
Symmetric data deduplication (SDD) reduces the amount of bandwidth consumed across a WAN link. You can enable symmetric data deduplication on the iSession™ connection between the local endpoint and any remote endpoints. SDD is enabled by default when you provision WOM®.
  1. On the Main tab, expand WAN Optimization and click Symmetric Deduplication.
  2. In the Maximum Number of Remote Endpoints field, type the number of BIG-IP WOM systems that you expect to connect to this one. This number specifies the maximum number of remote endpoints that can have symmetric data deduplication enabled, and thus, share the available cache. Any added WOM remote endpoint that exceeds this number receives no cache for deduplication. If you select SSD v2 in the Codec field, the maximum supported is 8. If you select SSD v3, the set value is 128.
  3. For the Enable Symmetric Deduplication setting, select Yes.
  4. For the Mode setting, select the method of storage for symmetric data deduplication.
    Option Description
    Disk Specifies that WOM uses the disk, in addition to memory, for storing information used for optimization.
    Note: If you enable data storage on the disk, you must restart the datastor service from the command line using the command sequence bigstart restart datastor for the change to take effect.
    Memory Specifies that WOM uses only memory for storing information used for optimization.
    Note: This setting can provide benefits for higher speed links.
  5. For the Codec setting, select the SDD version.
    Option Description
    SDD v3 Supports a high spoke count, such as for connecting remote sites and for mesh topologies.
    SSD v2 Supports a topology with fewer than eight spokes, such as replicating data between data centers.
    For SDD to occur between iSession endpoints, you must select the same codec on both the local and remote BIG-IP WOM systems.
  6. Click Update to save changes.
    Important: Updating any of these settings causes the deduplication cache to clear.
Symmetric data deduplication starts after an iSession connection is established with a remote endpoint that also has symmetric data deduplication enabled, provided that the number of remote endpoints does not exceed the value in the Maximum Number of Remote Endpoints field.
If you changed the Codec setting, the system applies the new setting to any new data flows. However, if you enabled or disabled SDD, you must then restart the BIG-IP WOM from the command line using the command sequence bigstart restart.

Disabling symmetric data deduplication

You can disable symmetric data deduplication on the iSession™ connections between the local endpoint and any remote endpoints.
  1. On the Main tab, expand WAN Optimization and click Symmetric Deduplication.
  2. For the Enable Symmetric Deduplication setting, select No.
  3. Click Update to save the change.
  4. Restart the BIG-IP WOM from the command line by typing bigstart restart.
Symmetric data deduplication stops on all iSession connections between the local endpoint and any remote endpoints, and the deduplication cache clears.
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