Disk space requirements

Before installing the CDC Replication software, you need to ensure that sufficient disk space is available on your server.

Disk space
CDC Replication source system:
  • 5 GB—For installation files, data queues, and log files.
  • Global disk quota—Disk space is required on your source system for this quota which is used to store in-scope change data that has not been committed in your database. The amount of disk space required is determined by your replication environment and the workload of your source database. To improve performance, CDC Replication will only persist LOB data to disk if RAM is not available. Use the mirror_global_disk_quota_gb system parameter to configure the amount of disk space used by this quota.
CDC Replication target system:
  • 5 GB—For installation files, data queues, and log files.
  • Global disk quota—Disk space is required on your target system for this quota which is used to store LOB data received from your CDC Replication source system. The amount of disk space required is determined by your replication environment and the amount of LOB data you are replicating. The minimum value is 1 GB. To improve performance, CDC Replication will only persist LOB data to disk if RAM is not available on your target system. Use the mirror_global_disk_quota_gb system parameter to configure the amount of disk space used by this quota.
CDC Replication may require additional disk space in the following situations:
  • You are running large batch transactions in the database on your source system.
  • You are configuring multiple subscriptions and one of your subscriptions is latent. In this type of scenario, CDC Replication on your source system may persist transaction queues to disk if RAM is not available.
  • You are replicating large LOB data types.
  • You are replicating "wide" tables that have hundreds of columns.
  • You are performing regular back ups of your metadata with the dmbackupmd command-line utility.