Re: onstat -F output
> Hi all,
> I have Informix 7.30.UC2 running on SCO 5.04 and have noticed this on
> my onstat -F output
>
> Fg Writes LRU Writes Chunk Writes
> 0 0 18463
>
> address flusher state data
> 874484c4 0 I 0 = 0X0
> 87448974 1 I 0 = 0X0
> 87448e24 2 I 0 = 0X0
> states: Exit Idle Chunk Lru
>
> This is an OLTP system so the LRU writes should be something other than 0
> am I correct? Also is noticed that even when a check point occurs my flushers
> stay idle. Am I missing something here?
>
> here is my onconfig file
Yes, you would probably expect (desire) some LRU writes on an OLTP system. I'm
assuming that you're experiencing long checkpoint durations - otherwise why are
you concerned about no LRU writes, right?
Looking at the onconfig file, do you think you have 12,800 pages get dirty in 5
minutes? With BUFFERS=32000 and LRUMAXDIRTY=40, no LRU writes will occur until
12800 pages are dirty. Actually, it's not quite that simple. With LRUS=8, an
LRU write will be triggered when any of the LRU queues gets 1600 pages dirty.
Put in a simple script to perform an 'onstat -R > logfile' every 5 or 10 seconds
for 15 minutes or so, then see how full your LRU queues are at their most-full
point. Adjust LRUMAXDIRTY and LRUMINDIRTY downward to force the LRU writes.
Mark Collins
mcollins@us.dhl.com