Fw: Long checkpoints causing crashes

Have you tried much lower values for LRU_MAX_DIRTY & LRU_MIN_DIRTY then default ? Like 10 and 5 respectively. You can go for even lower values. This will spread out I/O between checkpoints, instead of doing all the flushing at checkpoint. Pl. tell me your checkpoint interval and values for LRU_MAX_DIRTY & LRU_MIN_DIRTY. Also tell me about how many disks you have and how many LRUS you have. Alkesh Vipani. > ----- Original Message ----- > From: "William Rice" <ricew@operamail.com> > To: "Dominic Penfold" <bigbaddom_the_first@yahoo.com>; "informix-list" > <informix-list@iiug.org> > Sent: Friday, February 11, 2000 10:32 AM > Subject: RE: Long checkpoints causing crashes > > > > >===== Original Message From Dominic Penfold > <bigbaddom_the_first@yahoo.com> > > ===== > > >Hi There > > > > > >Running IDS 7.30.UC7 on HP-UX 10.20, and the server is > > >now hanging most evenings. This seems to be due to > > >long checkpoints, you often see one checkpoint of 80 > > >seconds or so, immediatley followed by a 2nd > > >checkpoint of 0-11 seconds or more, followed by > > >Informix Dynamic Server Stopped. > > > > What is your check point interval? > > > > >I've heard an idea to reduce the number of buffers, > > >saying this will lower checkpoint times and reduce the > > >problem. This is from the same person who had BUFFERS > > >set to 30000 when I first arrived, with tons of > > >ovbufs, bufwaits, and pathetic read and write caching, > > >I have now set BUFFERS to 180000 on this 3 gig phys > > >memory system, still below the 20-25% recomended. Note > > >any advice for BUFFERS setting on a machine that > > >shares informix with another application? onstat -p > > >shows much better performance now, but could it > > >actually be a good idea to cripple the system with a > > >crap number of BUFFERS, just to avoid stopping the > > >system with long checkpoints? > > > > The only reason lowering the number of buffers helps is > > that means the number of buffers you flush at the checkpoint is > > less (1 percent of 30,000 is less than 1 percent of 180,000) > > so by multiplying the number of buffers by 6 it is possible your > > checkpoints will be 5 or 6 times longer. > > > > > > > >Final note: I thought a core and shm dump may be a > > >good idea for tech support to analyse exactly why > > >informix is stopping, but I don't see how this is > > >possible, as it is not an assertion failure. > > > > Informix is most likely pausing for normal reasons. > > Could you post onstat -p, onstat -c, onstat -m, onstat -d > > > > > > Will > > > > ------------------------------------------------------------ > > This e-mail has been sent to you courtesy of OperaMail, as a free > service from > > Opera Software, makers of the award-winning Web Browser, Opera. Visit > us at > > http://www.opera.com/ or our portal at: http://www.myopera.com/ Your free > e-mail > > account is waiting at: http://www.operamail.com/ > > ------------------------------------------------------------ > > >