Re: EMC RAID-5 and MultiPlexing Redo Logs

From: Mike Towery <mtowery_at_yahoo.com>
Date: 5 Sep 2001 11:55:07 -0700
Message-ID: <2db8e790.0109051055.734bc004@posting.google.com>

"David Bye" <david_bye_at_bigpond.com> wrote in message news:<_5nl7.28$c5.63_at_newsfeeds.bigpond.com>...
> We are planning to deploy a 500GB database on EMC disks which are protected
> by RAID-5.
>
> Is there any value in also using multiplexing ?
>
> Thanks
>
> David

David,

First, let me say that Raid-5 is usually not a good choice for redo logs. Raid-5 is better for reading data and worse for writing and redo logs are extremely write intensive. (Although EMC will tell you otherwise because of the caching.) The value to multiplexing is that redo logs can become corrupted or erased without the underlying disks going bad. The trade off is between recovery and performance. If I determine the performance hit falls within my service level agreement with the users, I multiplex my redo logs for safety. Received on Wed Sep 05 2001 - 13:55:07 CDT