RE: Sudden Increase in Checkpoint Lengths

Keith. If you haven't done it already: set environment TRACECKPT=1; export TRACECKPT before starting IDS.That will make the checkpoints more chatty in online.log. If they are in critical section most of the time it could be an issue with the btscanners. HTH. Reinhard. > -----Original Message----- > From: informix-list-bounces@iiug.org > [mailto:informix-list-bounces@iiug.org]On Behalf Of John Carlson > Sent: Tuesday, August 11, 2009 3:04 AM > To: informix-list@iiug.org > Subject: Re: Sudden Increase in Checkpoint Lengths > > > Keith Simmons wrote: > > All > > > > Running IDS 9.4 FC6 on AIX 5.3, application written in INFORMIX-4GL > > Version 7.32.FC3. > > (I know it's a bit old, but it runs well (till now !!)) > > Around Friday lunchtime the checkpoint times on this server jumped > > from between 0 and 1 second to between 30 and 60 seconds (although > > many are running arounf 6 to 10 seconds, big variances). Even though > > the checkpoints are fuzzy (with several thousand buffers not being > > flushed) the users are being blocked for this length of time every 5 > > minutes (and they are not happy !!!). All disk writes are > Chunk Writes > > (no LRU or Fg), buffers are only getting around 6% dirty between > > checkpoints with low and high set to 8%/15%. Capturing onstat -u > > during a checkpoint shows around 30 user sessions blocked on the > > checkpoint but no-one in a critical section > > Except for an engine bounce (planned) about 4 weeks ago, the engine > > has run continuously with no configuration change for over > 9 months. > > There have been no application changes for the past 7 days. > > Only clue to the long checkpoints was a couple of 'Failed > _aioreturn' > > errors on each of two separate (unrelated) chunks in the online log. > > The O/S logs shows these errors also, but only as isolated entries, > > nothing continuous or on-going, also there are no hardware error > > lights illuminated nor does the DS4000 monitoring software show any > > issues. > > I have run page checks on the chunks with no errors and am currently > > running -cxI and -cd on each table in the DBSpaces involved. > > Any suggestions where else to look? > > > > Any issues with disk in the syslog (or AIX's version of syslog)? > > JWC > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list >