Re: CHECKPOINTS

Hi Mario,

I should also have asked for the size of the log files, and the values of log_checkpoint_interval and log_checkpoint_timeout, just in case you are checkpointing too intensively for a checkpoint to finish before the next one starts.

Regards,
Steve Adams

http://www.ixora.com.au/
http://www.oreilly.com/catalog/orinternals/
http://www.christianity.net.au/

On Thu, 02 Mar 2000 04:05:48 GMT, steve.adams_at_ixora.com.au (Steve Adams) wrote:

>Hi Mario,
>
>This is a DBWn bottleneck.
>Some questions ...
>
>What version of AIX?
>Is aio available (it should be)?
> To find out, do the following as root
> # smit aio
> select "Change/Show Characteristics of Asynchronous I/O"
>How many datafiles do you have?
>How many physical disks (spindles) underlying the data files (not
>counting log files)?
>What are the values of the following parameters?
> use_async_io
> db_writers
> db_files
> db_file_simultaneous_writes
> _db_block_write_batch (if set)
> db_block_checkpoint_batch
> db_block_buffers
> db_block_size
>
>Regards,
>Steve Adams
>http://www.ixora.com.au/
>http://www.oreilly.com/catalog/orinternals/
>http://www.christianity.net.au/
>
>
>On Wed, 1 Mar 2000 23:12:32 +0100, "Mario" <mtechera_at_yahoo.com> wrote:
>
>>
>>We have a problem with redo log switching
>>when running large jobs. All groups fill up
>>and remain active even though they
>>are archived - presumably this is because
>>checkpointing is going on.
>>
>>Finally when the
>>last log group fills and wants to switch back to
>>the first group it cannot do so, because
>>the first group is still active. At this point the system
>>slows to a crawl and even trivial queries require minutes
>>for a response.
>>
>>We have
>>increased the number of redo log groups
>>(almost doubling the space available),
>>and have also increased the initialization
>>parameter db_block_checkpoint_batch
>>so as to allow for faster checkpointing.
>>Yet the problem persists.
>>
>>Does anyone have any pointers for us?
>>
>>Is there any good documentation on how the checkpoint
>>process works and why it takes so long?
>>
>>Our System
>>Oracle V7.3.4, RS/6000, 2CPUs, 1.3 GB Memory, AIX
>>
>>Thanks in advance,
>>Mario
>>
>>
>>
>>
>
Received on Thu Mar 02 2000 - 00:00:00 CST