Re: Please help on BUFFERS configuration
What versions of online and OS are we talking about here?
On Tue, 09 Jun 1998 10:57:35 -0400, "Art S. Kagel"
<kagel@bloomberg.net> wrote:
>Fernando Collalti wrote:
>
>> Question:
>> The actual BUFFERS=20000, the physical memory is 256MB RAM, I would like to
>> increase
>> the BUFFERS to 40000, because I have to many buffers waits and the "Read %
>> cached" is to
>> low (86.16).
>> When I change the BUFFERS parameter from 20000 to 40000, in order to take
>> effect, I need
>> to bring down the engine (initialize), will my data be safe? Is changing
>> this critical parameter
>> safe?
>
>> CLEANERS 14 # Number of buffer cleaner processes
>
>> LRUS 14 # Number of LRU queues>
>Yes this is perfectly safe. Just bring the engine off line (onmode -sy
>and wait for all processes to detach or onmode -ky and force everyone
>off). Then modify the ONCONFIG file and run oninit (WITHOUT THE '-i'
>parameter which would INITIALIZE the root dbspace and wipe out your
>databases) to bring the engine back online.
>
>BTW, while increasing BUFFERS will help your READ CACHE % the bufwaits
>is more dependent on the number of LRU queues. There is also a bug, or
>at the very least a suspected bug, that causes very high bufwaits at
>certain numbers of LRU. Until now the only known such values are 64
>and 96, perhaps 14 is another node in this function?! Try increasing
>LRUS and CLEANERS to 32, this is a known good value and should be
>better for 40000 BUFFERS in any event. Please let me know what happens
>as I am tracking this bufwaits problem.
>
>Art S. Kagel
Doug Hayes
Database Administrator, Senco Fasteners