FAST_RESTART_PHYSLOG

onconfig.std value

The FAST_RESTART_PHYSLOG parameter does not need to be in the onconfig.std file.

range of values

0 (default) = Disable physical logging on fuzzy checkpoints during the roll-forward (log replay) phase of recovery.

1 = Enable physical logging on fuzzy checkpoints during the roll-forward (log replay) phase of recovery, thus decreasing recovery time.

takes effect

Immediately. If the total number of unflushed, fuzzy dirty pages exceeds 20 percent of the total physical log space, the pages will not be written to the physical log. However, if the database server fails before the next checkpoint performs, maximum fast-recovery performance does not occur because the database server did not log all of the fuzzy updates in the checkpoint intervals.

refer to

Information on fast recovery and alternative fast restart recovery options for fuzzy operations in the IBM Informix Administrator's Guide

The FAST_RESTART_PHYSLOG parameter and the FAST_RESTART_CKPT_FUZZYLOG parameter enable the database server to perform physical logging on fuzzy checkpoints during the roll-forward (log replay) phase of recovery, thus decreasing recovery time. You can use either parameter or both when using fuzzy checkpoints.

Only use the FAST_RESTART_PHYSLOG parameter if the buffer pool is at least 25 percent larger than the physical buffer size. The buffer pool must be large enough to hold the physical log, log pages, and other pages read during recovery. If the buffer pool is not configured correctly, fast recovery performance is compromised.

The extra physical logging that occurs when the database server uses the FAST_RESTART_PHYSLOG parameter affects runtime performance. If you do not want to sacrifice runtime performance or if you do not want to increase the buffer size, use the FAST_RESTART_CKPT_FUZZYLOG parameter to reduce some recovery time.

After enabling the FAST_RESTART_PHYSLOG parameter by setting it to 1 , you can initiate fast recovery using the oninit utility. Simply execute oninit without any options.

The database server must be online when you enable the FAST_RESTART_PHYSLOG parameter.