Re: Redo group members - are they written to in parallel?

From: Andrew Babb <andrewb_at_mail.com>
Date: Mon, 12 Apr 1999 07:48:28 +0800
Message-ID: <371134CC.65F2C55D@mail.com>

Back in the days of Oracle7 v7.1, I was implementing a 7x24 system, and we did some testing on Redo Log Members.

When the members were on File Systems, and could not take advantage of Async I/O, the time to write to 2 Members over that of one member was approx 2.1 : 1.

When we put the Redo Logs on RAW Devices, and thereby enabled Async I/O the write times went to approx 1.1 : 1.

When I spoke to Oracle, they confirmed that the writes were infact done Serially.

I am not sure what the rules are in Oracle8, but the way I tested was to just create a very large insert loop and timed the execution.

Hope this helps,
Andrew

Rob Bailey wrote:

> The question is in the subject - I have observed the last update times of
> redo log members and they dont seem to be in seqence - does anyone know for
> sure if they are written to in parallel?
>
> Or am I just wrong?
Received on Sun Apr 11 1999 - 18:48:28 CDT