Re: Help me tuning this wait event:log file sync

Hi, Howard,

Writing log entries is parallelized (wait event: log file parallel write). Only log file headers are written sequentially. This means that the same log entries are written to all members of a log group. If the written data is wrong, it's wrong in all members. Think carefully when you say "LGWR makes an error". It can mean Oracle's error or the error of anything underneath (OS, RAID hardware). The underlined OS or hardware only replicates Oracle's error. Are you saying LGWR can write correct logs to one member but corrupt logs to another?

Yong Huang

you wrote:

waiting to happen if that's all you've got. LGWR makes an error writing to
your one member -and the hardware immediately replicates that corruption onto your mirror(s). You've now got two identical copies of useless redo

-- 
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG