script to predict checkpoint
Posted in 2003
Hi,
I have a script in perl which can accurately predict when the next
checkpoint is due (upto 5 seconds off) and issue onmode -B just
before the checkpoint is due. This way, when Informix enters critical
stage of checkpoint, it will find lot less dirty buffers and block
the server for less time. In our case it blocks for only 0 or 1 seconds.
It writes to online log file accordingly. A sample
16:23:27 buffer_flusher is flushing buffer ....
16:23:54 Checkpoint Completed: duration was 0 seconds.
16:23:54 Checkpoint loguniq 961, logpos 0x4ee7018
This refers to only checkpoint occurring due to CKPINTVL, and not
unscheduled checkpoint like 75% physical log full, or backup started
etc. If any of those happens, the script will not issue onmode -B
but will continue to look for next scheduled checkpoint.
If anyone is interested, send a mail to s r k r i s h n a @ y a h o o.com.
cheers.