Re: Log file I/O throughput

"Yong Huang" <yong321_at_yahoo.com> wrote in message news:b3cb12d6.0308130744.6f16d704_at_posting.google.com...

> I found Steve Adams' notes at
> http://www.ixora.com.au/tips/use_raw_log_files.htm. He says "Hardware
> mirroring can be used in preference to redo log multiplexing to avoid
> serial writes to multiple log file members, and indeed such hardware
> mirroring is recommended to minimize the CPU cost of redo writes." I
> think in the first part he was referring to serial writes to _headers_
> of log file members, because writing to log file bodies would be
> parallelized. But parallel writes still cost CPU (his second part).

The bottom line I think is: Steve says "can be used", he doesn't say "must be used". Ie, it's an option. If you are confident enough on redundancy in your hardware and know that it is being managed by sensible people who know what they're doing, nothing to stop you from doing this.

I ran a site with non-mux redo logs for 4 years on an EMC, not a single failure. Then again, I trusted the SAN administrator and what he did to ensure the reliability of his box. Great performance on updates. Queries were another thing, but those had nothing to do with redos...

--
Cheers
Nuno Souto
wizofoz2k_at_yahoo.com.au.nospam