Re: Extended checkpoint times

In article <6a56qu$omb@cssun.mathcs.emory.edu>, Felix Koshy Mathews <fmathews@systems.DHL.COM> writes >anonymous wrote: > >> <snip> > >> We are trying to investigate a series of overly long checkpoints on one >> of our informix databases, here is >> a snippet of the online.log file detailing the events: >> >> <snip> > >> 21:55:42 Checkpoint Completed: duration was 3 seconds. >> 22:03:22 Checkpoint Completed: duration was 155 seconds.>> >> In general we have checkpoint times around the 6-7 second region, but >> recently we've seen several occurances >> were informix goes catatonic on us whilst doing a 400 second checkpoint! >> <snip> > >Mark, > >I have seen even bigger problem "Blocked Checkpoint", we haven't got any >satisfactory solution for this yet. This blocked checkpoint waits for ever I have seen it when running an archive. This checkpoints but if the tape drive hangs, the archive hangs, the checkpoint hangs and the server hangs. We had a checkpoint time of ~15,000 seconds!! Check that the logical logs are going to tape ok and that the archive tape drive is ok as well. What are your onconfig parameters? How many physical disks in the box and disk controllers. What is the disk layout? What does onstat -D show, are all the writes going to one chunk or disk drive? Try reducing LRU_MIN_DIRTY and LRU_MAX_DIRTY to 1 and 2. This will mean most page cleaning is done outside of checkpoints. Make sure you have plenty of CLEANERS configured and that the chunks have been created round robin across the disks. i.e. chunk 1 is not on the same disk/controller as chunk 2 etc. Generally one chunk per 2Gb disk. >!!!. This "Blocked Checkpoint" is not like any of the cases that we saw in >customer support registry. > >BTW, if you are afraid of spammers, add a "mailto" in your message text, >because some of us don't like to goof out on technical issues, with >anonymous guys, what is the guarantee that you are not my boss, with an >anonymous mask. > >-- >Have a nice day > >Felix K. Mathews >mailto:fmathews@systems.dhl.com > > -- David Williams Maintainer of the Informix FAQ Primary site (Beta Version) http://www.smooth1.demon.co.uk Official site http://www.iiug.org/techinfo/faq/faq_top.html I see you standin', Standin' on your own, It's such a lonely place for you, For you to be If you need a shoulder, Or if you need a friend, I'll be here standing, Until the bitter end... So don't chastise me Or think I, I mean you harm... All I ever wanted Was for you To know that I care