ptlrs commented on PR #9947: URL: https://github.com/apache/ozone/pull/9947#issuecomment-4086439416
Thanks for taking a look @errose28. Using secondary instance had crossed my mind while writing this PR but that page was the reason I didn't make the change. In fact I saw this comment in a [different discussion](https://github.com/facebook/rocksdb/issues/9967#issuecomment-1120517062) which says: >Read-only instances has only the state of the db when the read-only instance is opened. It's not meant to be used when the db is also opened by a normal DB instance. The normal db instance can cause file deletions unaware to the read-only instance. Future reads issued to the read-only instance may hit IOError due to trying to read from non-existing files. So based on the documentation and the comment, to me it appears that unless you actually perform any reads in RO mode, there won't be a problem. We don't perform any reads during the volume check but RocksDb does read the metadata from the footer of all SST files as well the MANIFEST files and the WAL when it is opened in RO mode. If that is where the problem is then, not sure if using a secondary instance would solve our problem. Secondary instance appears to be the same as RO instance with the extra capability of bringing the instance upto speed with the RW instance using a manual command invocation. This is nice to have but useful only if you actually read the data. I don't mind changing to secondary instance, as at worst we would get the same behavior but it would be good to brainstorm what could be the differences. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
