Re: Negative write caching rate

Hi, Sorry I don't have any sysmaster database here. I remember some table (sysbuffers? sysbufhdr?) where there should be a column indicating if the page has been modified. Sorry my info can't be more accurate at this moment, but hope it helps. -- Jos' Luis Matute Responsable Division Sistemas D&D Grupo Dydes Poligono EUROPOLIS Edif. Al Andalus Calle X, n' 4 y 6 28230 Las Rozas (Madrid) Tf: +34 91 6407080 Fax: +34 91 6373280 malcolm.weallans@btopenworld.com dijo: > I have been researching write caching rates in an attempt to explain > why a number of the sites that I oversee are seeing low write caching > rates. In the process I did discover that their level of OLTP write > activity is small which means that the basic system administration > functions adversely affect the caching rate. > > But in the process I discovered that there are periods of time when the > write caching rate becomes negative. I have seen write caching rates > as high as -300% when measured over 1 hour. > > Further analysis has revealed that this occurs every time that a > non-fuzzy (sync) checkpoint is performed during a period of very low > levels of activity. The non-fuzzy checkpoint flushes a significant > number of pages compared with the the non-checkpoint activity levels > > My questions are:- > > How can I tell when these non-fuzzy checkpoints have been performed? > > Can I determine through a sysmaster query how many pages have not been > flushed? > > regards > > Mighty M > > sending to informix-list