RE: Frequency of Log Switches

It seems people are arguing over semantics, and the original poster was = asking the wrong question. All he wanted was to not lose more than 15 = minutes of data if he crashed. This is controlled by checkpoints, NOT log = switches.

Setting the parameters Kieran mentioned appropriately will accomplish that = (along with FAST_START_IO_TARGET if using 8i). The INTERVAL parameter = specifies the maximum number of OS blocks you wish to be read in case of = instance recovery. The TIMEOUT one specifies the maximum seconds of blocks = you wish to read which obviously is much more ambiguous and why I believe = Satar suggested staying away from it. If you are pre-8i these parameters = have different meanings.

If you wish to force a log switch, ALTER SYSTEM SWITCH LOGFILE; but that = is only going to increase IO on your system and gain you nothing.

Michael Ray
Oracle DBA
TRW, Marshall, IL
217-826-3011 x2438

>>> ASAURY_at_recherche.loreal.com 11/30/00 04:55AM >>>
I beg to differ : I am running 8.1.6 on NT with log_checkpoint_timeout =3D = 300
and can have as much as 40 minutes between log switches.

I suppose that forcing a checkpoint does not forces a log switch (whereas the log switch forces the checkpoint).=20

Anybody having an idea on how to force a log switch ? Alain.

        -----Message d'origine-----

        Steven,

        try changing the initialization parameter LOG_CHECKPOINT_TIMEOUT = to
be 900

        and set the LOG_CHECKPOINT_INTERVAL to be a very high value = (greater
than

	the size of the redo logs),
	this will cause log switches every 15 minutes or when the log file
is full.
	Both of these values can=20
	be dynamically altered using ALTER SYSTEM.

	Regards,
	Kieran Murray
	Norkom Technologies,
	43 Upper Mount Street, Dublin 2, Ireland