CLIENTDEDUPTXNLIMIT

When you use client-side deduplication for large objects, intensive database activity can result from long-running transactions that are required to update the database. High levels of database activity can produce the following symptoms:

• Reduced throughput for client backup and archive operations
• Resource contention resulting from concurrent server operations
• Excessive recovery log activity

The extent to which these symptoms occur depends on the number and size of objects being stored using client-side data deduplication, the intensity and type of concurrent operations taking place on the Tivoli® Storage Manager server, and the Tivoli Storage Manager server configuration.

With the CLIENTDEDUPTXNLIMIT server option, you can specify a maximum size, in gigabytes, for transactions when client-side deduplicated data is backed up or archived. If an object or set of objects in a single transaction exceeds the limit specified by CLIENTDEDUPTXNLIMIT, the objects are not deduplicated by the client, and the transaction can fail. You can specify a value 32 - 2048 GB. The default value is 300 GB.

If an object or set of objects in a single transaction exceeds the limit specified by CLIENTDEDUPTXNLIMIT, the objects or set of objects is not deduplicated by the client. However, the objects are sent to the server. These objects can be deduplicated on the server, depending on whether the destination storage pool is configured for data deduplication and on the value of the SERVERDEDUPTXNLIMIT option. Objects in a deduplication-enabled storage pool that are less than the value of the SERVERDEDUPTXNLIMIT are deduplicated by a server duplicate-identification process.

The appropriate value for this option depends on the Tivoli Storage Manager server configuration and concurrent server activity. You can specify a high value for this option if you minimize resource contention. To minimize resource contention, perform operations, such as backup, archive, duplicate identification (the IDENTIFY DUPLICATES command), and reclamation, at different times.

To update this server option without stopping and restarting the server, use the SETOPT command.

                        .-300-------.   
>>-CLIENTDEDUPTXNlimit--+-gigabytes-+--------------------------><

Parameters

gigabytes

Specifies the maximum size, in gigabytes, of objects that can be backed up or archived using client-side data deduplication. You can specify a value 32 - 2048. The default value is 300.

clientdeduptxnlimit 80