Re: page cleaner #1 timed out

Tracy Nedd wrote: > > Guy, > The I have seen this error caused by the following condition: > Having too many page cleaners defined with respect to the number > of actual disks. > > If you only have one physical disk but it's partitioned into > 5 logical chunks and each chunk has been used for a dbspace, > how many page cleaners would you set in the config file? Most > folks set up one per chunk, but in this case that's not the > right thing to do. > > The problem comes up because the LRU queues are divided among > the page cleaner threads. That way they can flush the buffers > in parallel. But if you only have one physical disk then the other > page cleaners must wait until the first one is done before being > able to write to disk. > > Sometimes the page cleaners at the end of the queue reach a preset timeout > limit and die off. There's no way to restart them except by downing/up > the engine. But if they're dying off in the first place, then lower > the number of page cleaners or (like someone else suggested) change > your LRU_Dirty parameters so that each page cleaner works on smaller > data sets. Then they will finish faster and pass the torch onto the > next page cleaner, hopefully before it times out. > > HTH, > > Tracy > > NOTE: I've always found that setting the number of page > cleaners = the number of physical disks + 1, has always worked for me. > > > > Online 5.03.UD2 on Compaq proliant 4500. From time to time we get the > > error > > "ERROR: page cleaner # 1 has timed out" > > > > What does it mean ? How can we solve it ? > > > > Guy. > > > > > > -- > ========================================================================= > = Tracy W. Nedd = > = Banctec Inc. - DBA = > = Silver Spring, Md = > = tracyn@asd.banctec.com = > ========================================================================= > = ALL RIGHTS RESERVED. = > = This posting is copyright and may be used only for the purposes = > = of professional study, or the professional exchange of information. = > = Use of this posting by any commercial organization for the purposes = > = of vilifying another is explicitly prohibited. = > ========================================================================= When taking an Informix class a few months ago, I was told by the instructor that when you create chunks do not add them consecutively on the disks. Let me explain: Let's says you decide on 3 page cleaners and you have disk A and disk B and each disk will have 3 chunks, then create them in this order A1, B1, A2, B2, A3, B3 and not A1, A2, A3, B1, B2, B3 because page cleaners will write in the order that chunks were added. So in the first config you'll have the page cleaners going to A1, B1 and A2 instead of A1, A2 and A3 and thus fighting for a device. Any comments?