0 Replies Latest reply: Feb 13, 2013 10:28 AM by EdStevens RSS

    looking for info on diskmon process

    EdStevens
      Oracle SE-One 11.2.0.1
      Oracle GI 11.2.0.2
      Oracle Linux 5.6 x86-64
      ASM is standalone, no RAC involved at all

      Last week I upgraded my GI from 11.2.0.1 to 11.2.0.2 and over the next few days notice a constant increase in disk usage on the mount point containing ORACLE_HOME. Tracked it down to a bunch of core dumps in ORACLE_HOME/log/<server>/diskmon. Research led to MOS note [1337867.1] and a couple of related bugs. Turns out that there are two diskmon processes running. One since the upgrade, the other dies and restarts every 10 minutes, throwing a new dump in the process.

      The fix is simple enough, just kill the older of the two processes. I've tested that on my sandbox and it seems clean enough. But I'd like to expand my understanding at this point.

      (first, as an aside, I thought it interesting that two very similar bug reports said 'no patch, could not reproduce'. Hmm, I was able to reproduce it with no effort at all ..)

      Here's my question. Just trying to get an understanding on exactly what diskmon does has not turned up much info. Searching the entire doc lib at tahiti only turned up two hits outside of the messages manual.

      http://docs.oracle.com/cd/E11882_01/server.112/e25513/bgprocesses.htm#REFRN104
      Oracle® Database Reference

      The only mention in this document is from a table listing several processes:
      http://docs.oracle.com/cd/E11882_01/server.112/e25513/bgprocesses.htm#REFRN104
      Oracle Database Reference
      
      DSKM     Slave Diskmon      Acts as the conduit    This process is active only if Exadata Storage is used. DSKM performs operations related    ASM instance, 
               Process            between the            to Exadata I/O fencing and Exadata cell failure handling.                                   Exadata
                               database, ASM 
                                  instances, and the 
                                  Master Diskmon 
                               daemon to 
                                  communicate 
                                  information to 
                                  Exadata storage
      Note that it says it's only used with Exedata. ?!?!

      And in http://docs.oracle.com/cd/E11882_01/rac.112/e16794/intro.htm#CWADD91998
      Oracle Clusterware Administration and Deployment Guide
      only includes it on a list of clusterware component, no explanation at all


      Any additional references are appreciated.