Re: Copying across databases

Thanks for all the responses and emails. It turns out the blockage was that they only effectively have one disk on their system (a mirrored pair to be exact), so it was clogging up trying to do reads and writes at the same time. The solution was to separate them. The most effective fix (I tried a good few) was implementing read-ahead, plus raising LRU_MIN/MAX_DIRTY to hive off most of the writes to checkpoints. Relatively small numbers of LRUS and page cleaners worked best, in fact it only seems to use one of the latter most of the time. Their checkpoints can get pretty horrific - fortunately OLTP users aren't on when they run the big stuff and OLTP writes are quite light so I can get away with it - but it was they that volunteered that that's the price you pay for cutting corners on spindles. It's now spending about 10% of the previous time doing reads and buffer shunting, but still about 90% of the time it was spending on writes. Hope this helps anyone who meets a single-disk installation. Andy