How to make sure that the data in stby is not more than 15 minutes

These two parms(CHECKPOINT and TIME) are different. One specified in seconds and other in # of blocks.

LOG_CHECKPOINT_INTERVAL specifies the frequency of checkpoints in terms of the number of redolog file blocks(OS blocks, not DB blocks) that can exist between an incremental checkpoint and the last block written to the redo log.

Regardless of this value, a checkpoint always occurs when switching from one online redo log file to another. Therefore, if the value exceeds the actual redo log file size, checkpoints occur only when switching logs.

Analyze this, assuming 512k is redolog size and 520k is LOG_CHECKPOINT_INTERVAL( interms of blocks). Though you specify at this INTERVAL checkpoint to occur, it occurs only when log switch occurs, as its just 512k.

Hope this helps...

[Edited by sreddy on 12-29-2000 at 11:20 PM]

Thanks all, especially Sreddy and Pando. I got it. Giving right parameters for Log Interval and Time out ensures the # of minutes desired recovery.

Thanks Everyone and I wish Great New Year for the whole Forum Group.

Quote:

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Originally posted by sreddy
I got it. Do what Pando suggested.

LOG_CHECKPOINT_TIMEOUT = 900

It will force log switch to occur as it flushes the dirty buffers(in cache) to redolog after specified time interval in sec.

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Unfortunately this wil not force a log switch. It will force a checkpoint everey 900 seconds, but the checkpoint and the log switch are not the same thing.

There is no init parameter to force a periodic log switch. The only way to do it is through a batch job, preferably through DBMS_JOB.

indeed, checkpoint wont cause log switch may be as suggested in previous try dbms_job

Yep! The only alternative way(other than using log switch command for every 15 min) is you can make log switch to occur :

Resize your logs in such a way log switch occurs every 15 minute until you upgrade your database to 9i which is not gonna happen soon.

This z what I have come up with at last, which you know already! :)


[Edited by sreddy on 01-02-2001 at 04:57 PM]

Hi SReddy,

We cannot always make sure to have a log switch by resizing the log file. I think it is very difficult if not impossible to plan a log file which fills every 15 minutes on production machine. As some times when they are doing some processing it gets filled every 1 minute. And some times it will not get filled even for 1 hour.

So is the reason I am looking for a better solution

Sizing your logfiles to switch every x minutes is next to impossible in the real world. How fast a logfile fills up is directly proportional to the transaction volume. If you size your logfiles to swith every x minutes during the heaviest transaction load, they will be oversized for normal load and might not even switch at other times. If you size your logfiles for normal load, they may switch quickly during peak periods. The key is to strike a balance between recoverability and performance with the business will dictate.


Kishore has a reasonable request. "How do I make sure my database does a logswitch every x minutes?" As several have suggested, it can only be done via a scheduled job (cron, batch, dbms_job, etc.) There are currently no init.ora parameters that will periodically force a log switch.

Thats TRUE, we can't predict the transaction volume at any point of time. So, we end up having no alternative to switch log file at specified time interval other than issuing a command. We got to go with that for 6 months more until they release 9i and it becomes stable... Good thread! Thanks for participants...

[Edited by sreddy on 01-02-2001 at 06:03 PM]

waitingfor 9i to become stable until end of this year .... probably :D