'Tuner Blog

Greetings fellow 'Tuners!  Returning yesterday afternoon from a college visit to Penn State, I missed FTOTM.  I did post updated files this morning, so have at it!  The rule set this month is focusing on transaction logging settings in the server document as well as a batch of DAOS/notes.ini rules to prevent premature attachment pruning.

I hooked up with some of our transacation logging folks to get some recommended values.  Consequently, the TRANSLOG_AutoFixup rule will detect whether or not you have auto fixup set in your server document (we recommend that you do.)  The TRANSLOG_Performance rule will determine what kind of performance is preferred for transaction logging.  The default is 'Standard'.  However, I/O performance improvements have been seen when 'Favor runtime' is set, so we now suggest this. 

In addition to the transaction logging rules, I was pointed to a set of notes.ini settings that can cause premature DAOS attachment pruning when enabled.  The following rules exist to let you know if you have these settings active when DAOS is enabled:

• DEBUG_DISABLE_CACHE_DB_UPDATES
  
• DEBUG_DISABLE_DIRECTORY_CACHE
• DEBUG_DISABLE_DIRMAN_REFRESH
• DEBUG_DISABLE_REFRESH_CACHE_FROM_DISK
• DEBUG_DISABLE_UPDATE_CACHE_DB

These rules were implemented in direct response to (and link back to) the technote Diagnostic (debug) NOTES.INI settings for dbdirman can cause DAOS to delete attachments prematurely.  Thanks to folks who sent these to me, internally and externally.  So, another month, another set of rules - are there spots that we are missing?  Things we could improve?  I'd really like to hear from you either via response or by email at sokeefe@us.ibm.com.  Enjoy!