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Hi,

We are trying to see what the optimal size of our redo logs should be
and how many we should have.

We are running 10g, and we know that there is the MTTR_ parameter.
But for now, we want to the the log_checkpoint......

We have a high transaction system. Currently we have 5 redo logs,
each 50M. We are still receiving the error "Check point not
complete".

I'm not sure if creating more groups is the answer, shrinking the log
size, or making the logs bigger. We are researching it, but in the
meantime this error is happening frequently.

We are looking for some advice on what to do given the path we want to
take......

Thanks for any help.

John.

On 28 Mar, 14:27, m...@mtekusa.com wrote:
> Hi,
>
> We are trying to see what the optimal size of our redo logs should be
> and how many we should have.
>
> We are running 10g, and we know that there is the MTTR_ parameter.
> But for now, we want to the the log_checkpoint......
>
> We have a high transaction system. *Currently we have 5 redo logs,
> each 50M. *We are still receiving the error "Check point not
> complete".
>
> I'm not sure if creating more groups is the answer, shrinking the log
> size, or making the logs bigger. *We are researching it, but in the
> meantime this error is happening frequently.
>
> We are looking for some advice on what to do given the path we want to
> take......
>
> Thanks for any help.
>
> John.

http://groups.google.co.uk/group/com...b3cbac042500c0

HTH

-g

On Mar 28, 9:41 am, gazzag <gar...@jamms.org> wrote:
> On 28 Mar, 14:27, m...@mtekusa.com wrote:
>
>
>
> > Hi,
>
> > We are trying to see what the optimal size of our redo logs should be
> > and how many we should have.
>
> > We are running 10g, and we know that there is the MTTR_ parameter.
> > But for now, we want to the the log_checkpoint......
>
> > We have a high transaction system. Currently we have 5 redo logs,
> > each 50M. We are still receiving the error "Check point not
> > complete".
>
> > I'm not sure if creating more groups is the answer, shrinking the log
> > size, or making the logs bigger. We are researching it, but in the
> > meantime this error is happening frequently.
>
> > We are looking for some advice on what to do given the path we want to
> > take......
>
> > Thanks for any help.
>
> > John.
>
> http://groups.google.co.uk/group/com...server/browse_...
>
> HTH
>
> -g

We are really hurting here:

NAME VALUE
------------------------------- ----------------
redo buffer allocation retries 18,887
redo log space wait time 324,520

On Mar 28, 9:41 am, gazzag <gar...@jamms.org> wrote:
> On 28 Mar, 14:27, m...@mtekusa.com wrote:
>
>
>
> > Hi,
>
> > We are trying to see what the optimal size of our redo logs should be
> > and how many we should have.
>
> > We are running 10g, and we know that there is the MTTR_ parameter.
> > But for now, we want to the the log_checkpoint......
>
> > We have a high transaction system. Currently we have 5 redo logs,
> > each 50M. We are still receiving the error "Check point not
> > complete".
>
> > I'm not sure if creating more groups is the answer, shrinking the log
> > size, or making the logs bigger. We are researching it, but in the
> > meantime this error is happening frequently.
>
> > We are looking for some advice on what to do given the path we want to
> > take......
>
> > Thanks for any help.
>
> > John.
>
> http://groups.google.co.uk/group/com...server/browse_...
>
> HTH
>
> -g


Also, we forgot this parameter:

SQL> show parameters log_buffer

NAME TYPE VALUE
------------------------------------ -----------
------------------------------
log_buffer integer 14286848

On Mar 28, 8:29*pm, m...@mtekusa.com wrote:
> On Mar 28, 9:41 am, gazzag <gar...@jamms.org> wrote:
>
>
>
>
>
> > On 28 Mar, 14:27, m...@mtekusa.com wrote:
>
> > > Hi,
>
> > > We are trying to see what the optimal size of our redo logs should be
> > > and how many we should have.
>
> > > We are running 10g, and we know that there is the MTTR_ parameter.
> > > But for now, we want to the the log_checkpoint......
>
> > > We have a high transaction system. *Currently we have 5 redo logs,
> > > each 50M. *We are still receiving the error "Check point not
> > > complete".
>
> > > I'm not sure if creating more groups is the answer, shrinking the log
> > > size, or making the logs bigger. *We are researching it, but in the
> > > meantime this error is happening frequently.
>
> > > We are looking for some advice on what to do given the path we want to
> > > take......
>
> > > Thanks for any help.
>
> > > John.
>
> >http://groups.google.co.uk/group/com...server/browse_...
>
> > HTH
>
> > -g
>
> Also, we forgot this parameter:
>
> SQL> show parameters log_buffer
>
> NAME * * * * * * * * * * * * * * * * TYPE * * * *VALUE
> ------------------------------------ -----------
> ------------------------------
> log_buffer * * * * * * * * * * * * * integer ** 14286848- Hide quoted text -
>
> - Show quoted text -

Your redolog size of 50M seems to be a very small size for a database
with high transaction load.We usually have 100Mb logs on normal
systems and on our high load OLTP system we have redologs of size
500MB.So try increasing your redo log file size and 5 groups seem to
be OK.
Also if you are on 10g,please check if many automated schedular jobs
are running or not.........there is one particular job that runs daily
to collect database statistics......if its really not needed u could
disable them and schedule your own jobs to collect
statistics.............

As far as the MTTR parameter is concerned.......you set yout
FAST_START_MTTR_TARGET to the time that you expect instance recovery
to take and oracle will take care of the rest of the things.....on
critical systems we set this to 300 seconds that is 5 minutes on
others we set it to 900 or 1800........

Regards,
singaravelan.dba@gmail.com

On Mar 28, 10:27*am, m...@mtekusa.com wrote:
> Hi,
>
> We are trying to see what the optimal size of our redo logs should be
> and how many we should have.
>
> We are running 10g, and we know that there is the MTTR_ parameter.
> But for now, we want to the the log_checkpoint......
>
> We have a high transaction system. *Currently we have 5 redo logs,
> each 50M. *We are still receiving the error "Check point not
> complete".
>
> I'm not sure if creating more groups is the answer, shrinking the log
> size, or making the logs bigger. *We are researching it, but in the
> meantime this error is happening frequently.
>
> We are looking for some advice on what to do given the path we want to
> take......
>
> Thanks for any help.
>
> John.

Are you seeing waits for log buffer space or for log file sync?

If you see "enough" waits for log buffer space you want to think about
making your memory based log buffer larger.

Log file sync you want to look at performance of IO to the online log
buffers.

Everything being equal and keeping in mind there are "no silver
bullets" for most modern systems there isn't a real benefit to making
online logs small. 500 meg up to several gig in size might make sense
for your environment. You can always force a log switch as desired.