Re: CHECKPOINTS

Hi, Steve

Thank you for pointing out the fact that ENABLE_CHECKPOINT_PROCESS will not "fix" Mario's problem. I agree. I should have made it more clear that this suggestion was just something in addition to more substantive action to improve I/O performance.

I was well aware that the CKPT process only frees up the LGWR somewhat, and that Mario's problem probably lies in the DBWR I/O realm.

On the other hand, enabling the CKPT process does, in my experience, help some (which is, I assume, why Oracle 8 made it a standard feature rather than an option). On occasion, "some" is enough to push the problem off (on rare occasion, enough to actually "cure" it).

Craig's paper includes information about I/O and so forth -- so I was just adding a couple of cents worth about something in the "can't hurt, might help" category.

I certainly would not expect turning on ENABLE_CHECKPOINT_PROCESS to have any dramatic effect on its own.

Thanks again.

        / Bob

"Steve Adams" <steve.adams_at_ixora.com.au> wrote in message news:38bdee81.39787591_at_news.eagles.bbs.net.au...
> Hi Bob,
>
> The checkpoint process is only responsible for the writes to the
> datafile headers, not the data block writes.
> Enabling it would not help Mario at all.
>
> Regards,
> Steve Adams
> http://www.ixora.com.au/
> http://www.oreilly.com/catalog/orinternals/
> http://www.christianity.net.au/
>
>
> On Thu, 02 Mar 2000 03:57:10 GMT, "Bob Beilstein"
> <rjbeilstein_at_earthlink.net> wrote:
>
> >In addition to Craig Shallhamer's excellent suggestions, you want to make
> >sure that you have:
> >
> >CHECKPOINT_PROCESS=TRUE
> >
> >set in your init.ora. This will start a separate process devoted to
 doing
> >checkpoint I/O.
> >
> >In my experience, it can make the difference between getting the log
 files
> >emptied before you roll back to them, and not.
> >
> >You also didn't mention how big your logfiles are. We've found that for
 a
> >lot of databases, increasing the size of the logfiles (we often use 64MB
 or
> >larger for big databases) can also help. Your mileage may vary.
> >
> >
> >
> >"Mario" <mtechera_at_yahoo.com> wrote in message
> >news:89k4d5$di0$1_at_news.online.de...
> >>
> >> 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 Fri Mar 03 2000 - 00:00:00 CST