In order to speed up the data transport or log shipping rates between primary and standby databases in a DataGuard environment, set the Oracle network services session data unit (SDU) to its maximum setting of 32K on both the primary and secondary databases. This can result a 5% gain in throughput over the default setting of 2K for LGWR ASYNC transport services and a 10% gain for the LGWR SYNC transport service.
When using the SDU setting, dynamic instance registration (SERVICE_NAMES) cannot be used prior to release 126.96.36.199. as it overrides any SDU setting to be the default SDU of 2K.
The SDU parameter needs to be set in listener.ora and tnsnames.ora on the primary and the standby databases.
Primary listener with static registration ----------------------------------------- LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = prim_host)(PORT = 1521))) ) SID_LISTENER = (SID_LIST = (SID_DESC = (SDU=32767) SID_NAME = prim_instance) ) ) Primary tnsnames.ora -------------------- primDB = ( DESCRIPTION = (SDU = 32767) (ADDRESS_LIST = (ADDRESS = (PROTOCOL = tcp)(PORT = 1521)(HOST = prim_host)) (CONNECT_DATA = (SID = prim_inst) ) )The same is required on the standby.
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This was first published in October 2003