Normally, a sufficient number of addresses of empty pages is available in the
system devspace and converter cache. These addresses are passed to the dev threads.At times when the
database instance is very busy and an above-average number of new pages is being added to it, the number of addresses available in the relevant pool of the main memory (the Pno pool) may drop below a certain level. When this happens, the conv scanner (a special user kernel thread (UKT)) quickly supplies the addresses of fresh empty pages by asynchronously finding page addresses in the system devspace which have been cleared for reuse by Delete or Drop.