scn,logseqno....help

[biju72]

Hi
Padmam and other moderators and friends

could any one tell what's major differnce between
fast_start_io_target,log_checkpoint_interval
how does it helps in instance recovery.
Does it speeds up instance recovery? or used to speed up checkpoints ?
What's major difference between logseqno,chkptno and scn ?

any help will be highly appreciated .

Bye
regards
Biju

[rohitsn]

Hi,
FAST_START_IO_TARGET specifies the no if I/O's that should be needed during crash or instance recovery.When u set this value,DBWR writes the dirty buffers more aggresively so that the number of blocks that must be processed during crash recovery stays below the value specified.Smaller values fo this parameter results in faster recovery times.
e.g. if ur db_block_buffers=10000 in init.ora and u set
fast_start_io_target=5000,so when an instance crashes
and during the recovery Oracle will have to recover only
5000 blocks which were there in buffer cache at time
when the instance crashed.

LOG_CHECKPOINT_INTERVAL specifies that when LGWR writes n no of redolog blocks(ie. os block) a checkpoint will occur.Regardless of this parameter checkpoint occurs when there is a switching of logfile.

Both this parameter has effect on the instance recovery but FAST_START_IO_TARGET which is new in oracle 8i has more effect on instance recovery.

In case of any help please be free to ask me at [email protected]

Regards,
Rohit Nirkhe,Oracle DBA,OCP 8i
[email protected]