From: Martin Brown <>
Date: Tue, 9 Dec 2008 16:17:15 -0500
Message-ID: <BAY119-W25EED00F8BFDA3BA98CD05C2FA0@phx.gbl>

I have a similar question regarding raid 5 and what I perceive to be a "potential" problem. I am experiencing a high number of logfile sync waits that appear most afternoons as the daily load starts to increase. We're running RAC with a 8 node cluster. We use a 3par storage system for the database. My architect has configured both raid 1 and raid 5 diskgroups and he duplexes the online redo logs and controlfiles to raid5.  

Now, he insists that the logfile sync waits are not related in any way to the raid5 configuration and the 3par storage solution is state-of-the-art. But the only remedy I can find is to move to faster SSD. Is it possible that the high afternoon activity coupled with the raid5 configuration is the root of my problem?  

I've looked at other stuff too. The log switches are 2 - 3 an hour. The log buffer is never full. Anyone have any other suggestions as to where to look?

Subject: DB RAID SetupDate: Tue, 18 Nov 2008 17:06:20 +0000From:


Oracle 10g2 (data warehouse)  

I thought I would ask peoples’ thoughts on the following.  

I have setup our database whereby the index tablespace and data tablespace are separate. This is not for performance reason only for ease of maintenance.  

We are being advised by the SAN provider to use the following RAID layout  

                Archive redo Logs            - RAID 10
Redo Logs                           - RAID 10
Temp tablespace             - RAID 10
Undo tablespace              - RAID 10
Index tablespaces           - RAID 10
System tablespace          - RAID 5
Data tablespaces              - RAID 5

Redo logs / Temp tablespace I agree with.  

To use RAID 5 for data, I understand there is a write performance hit but this is a data warehouse so should be ok (Ideally I would like that RAID 10 as well). But to have the index tablespace on RAID 10 and data tablespace on RAID 5 I found that strange. When I asked the reason why I was give the response ‘that is what Oracle recommends’.  

Has anyone heard this before?  


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Received on Tue Dec 09 2008 - 15:17:15 CST

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