Log files in Online 5.x 
Author Message
 Log files in Online 5.x
Can anybody tell me an easier method for changing th logfile size on
I-Online 5.x than unloading the whole database and reloading it with a
new size? When we went through and redesigned the dbspaces and table
distribution, we brought the system back up with very small log files.
This is killing us with long transaction aborts. Can anybody help?
Thanks,

Dave



Wed, 18 Jun 1902 08:00:00 GMT
 Log files in Online 5.x

Quote:
> Can anybody tell me an easier method for changing th logfile size on
> I-Online 5.x than unloading the whole database and reloading it with a
> new size? When we went through and redesigned the dbspaces and table
> distribution, we brought the system back up with very small log files.
> This is killing us with long transaction aborts. Can anybody help?

There are several things you can do:
        1)  add more logs
        2)  change the size of the existing logs (without unloading/loading)
        3)  move the logs on disk (the physical and logical log *files*)
        4)  adjust high-water marks (are they too low?)
        5)  adjust locks while you're at it (lock level and number)

But first, you should take the OnLine Database Administrator's course.
Then, (no, before), RTFM.  The "Informix OnLine Administrator's Guide"
contains an entry in the index for "changing the size of the logical
logs", and a very thorough explanation of the process.  

Of course, you can get some extra explanation in Joe Lumbley's book:
"Informix Database Administrator's Survival Guide", available from
Informix Press (ISBN 0-13-124314-4).

If you get confused or find something contradictory after all that,
just give a shout.
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Wed, 18 Jun 1902 08:00:00 GMT
 Log files in Online 5.x
dave,

Quote:
> Can anybody tell me an easier method for changing th logfile size on
> I-Online 5.x than unloading the whole database and reloading it with a
> new size? When we went through and redesigned the dbspaces and table
> distribution, we brought the system back up with very small log files.
> This is killing us with long transaction aborts. Can anybody help?
> Thanks,

        in 5.X there is nothing you can do about this, short of unloading
and loading.  but why not up LOGSMAX, and just add a bunch more log files?
give them their own dbspace as well.   the size of the log file doesn't
*really* matter, (it does, in terms of how much transaction data is there
that isn't logged to tape, etc...), but as far as transaction aborts, it's
the number of files that you have.

        we have 7.11 running in an environment with ~70 sessions at a time,
running mostly oltp and some dss.  i have 60 log files, 1000k each, sitting
in 2 dbspaces.  the first dbspace has all the odd numbered logs, and the second
all the even.  this way there is less disk contention, as ontape reads the
disk to back up the previously written log, the system is accessing another
disk to write the current log.

        hope this helps.

        mickm



Wed, 18 Jun 1902 08:00:00 GMT
 Log files in Online 5.x
Why so much log space? Recommendation is for physical and logical log is
20% of your total configuration disk space. With a 3:1 ratio between the
logical and physical log space. If this is not correct (or if many of you
have found not to work), plese let me know.

Thanks!!!!

 -------------------------------------------------------------------------
 Cheryl Kendricks

                      OR

                      OR

 DTSI, Inc.                      Voice: 1-800-598-5008
 Database Administrator - DOL Job Corps San Marcos, Texas
 ------------------------------------------------------------------------

Quote:

} dave,
}
} > Can anybody tell me an easier method for changing th logfile size on
} > I-Online 5.x than unloading the whole database and reloading it with a
} > new size? When we went through and redesigned the dbspaces and table
} > distribution, we brought the system back up with very small log files.
} > This is killing us with long transaction aborts. Can anybody help?
} > Thanks,
}
}       in 5.X there is nothing you can do about this, short of unloading
} and loading.  but why not up LOGSMAX, and just add a bunch more log files?
} give them their own dbspace as well.   the size of the log file doesn't
} *really* matter, (it does, in terms of how much transaction data is there
} that isn't logged to tape, etc...), but as far as transaction aborts, it's
} the number of files that you have.
}
}       we have 7.11 running in an environment with ~70 sessions at a time,
} running mostly oltp and some dss.  i have 60 log files, 1000k each, sitting
} in 2 dbspaces.  the first dbspace has all the odd numbered logs, and the second
} all the even.  this way there is less disk contention, as ontape reads the
} disk to back up the previously written log, the system is accessing another
} disk to write the current log.
}
}       hope this helps.
}
}       mickm
}



Wed, 18 Jun 1902 08:00:00 GMT
 Log files in Online 5.x
Hi,

Unfortunately the only way I know of to change the log file size
is to re-initialize. You can however add more log files which will
help the long transaction situation. Just add some logs and then
do a level 0 archive to enable them.

-Bill

Quote:

> Can anybody tell me an easier method for changing th logfile size on
> I-Online 5.x than unloading the whole database and reloading it with a
> new size? When we went through and redesigned the dbspaces and table
> distribution, we brought the system back up with very small log files.
> This is killing us with long transaction aborts. Can anybody help?
> Thanks,

> Dave

--
Bill Ennis                           Voice: 312-474-7516
SSA                                  Fax:   312-474-7460



Wed, 18 Jun 1902 08:00:00 GMT
 Log files in Online 5.x
cheryl,

Quote:
> Why so much log space? Recommendation is for physical and logical log is
> 20% of your total configuration disk space. With a 3:1 ratio between the
> logical and physical log space. If this is not correct (or if many of you
> have found not to work), plese let me know.

        like most of the other parameters, these are guidelines to start out
with.  on my system, with my 60 logs, and LTXHWM at 50 and LTXEHWM at 60, the
standard recommendations, i'm still seeing a few aborted long transactions
a day.  a percentage of these truly are long transactions that should be
aborted, but a lot of them aren't.  some of them ran fine on the 5.0 system,
it seems that more data makes it into the log files under 7.X.

        so i still need to up the number of logs that i have.  i will probably
add another 10 log files today and see how that goes.

        mickm

Quote:

> >       we have 7.11 running in an environment with ~70 sessions at a time,
> > running mostly oltp and some dss.  i have 60 log files, 1000k each, sitting
> > in 2 dbspaces.  the first dbspace has all the odd numbered logs, and the seco



Wed, 18 Jun 1902 08:00:00 GMT
 
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