Subject: Inquiry Regarding Archive Log Directory Structure for Oracle RAC + ASM with Debezium CDC
marcellov
Hello,
I am currently preparing to implement CDC for a customer using Debezium.
The environment consists of an Oracle RAC system with two nodes, and the archive logs are stored on shared storage configured with ASM.
I would like to confirm the correct directory structure for storing archived redo logs in this configuration.
Some documentation suggests that the archive logs for each instance may be separated, e.g.,
node1/archive.log and node2/archive.log.
However, other documents state that all archive logs must be consolidated into a single shared location such as total/archive.log.
Before proceeding, I want to ensure that we follow the proper guideline or best practice for Debezium LogMiner-based CDC in an ASM-backed Oracle RAC environment.
As this message was translated, please excuse any grammatical imperfections.
Thank you in advance for your assistance.
Best regards,
Chris Cranford
Debezium does not care about the physical location on disk where the logs are stored, but rather what LOG_ARCHIVE_DEST_n (where n is 1 to 31) mapping is used. I've never tried nor setup an Oracle instance where a single LOG_ARCHIVE_DEST_n mapping was to different directory paths by nodes. That doesn't mean that it isn't possible, but it's not common if permitted.
What Debezium does is find the LOG_ARCHIVE_DEST_n mapping where the destination is TYPE=LOCAL and STATUS=VALID. If you have only one mapping, then we use that by default. If you have multiple mappings configured this way, you will need to specify the archive.destination.name, which specifies the LOG_ARCHIVE_DEST_n mapping to be used.
We simply provide the paths as they exist in V$ARCHIVED_LOG to LogMiner, and it is responsible for all Disk IO.
Hope that helps.
-cc
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