Re: Exadata high capacity vs high prformance drives

From: Carol Dacko <>
Date: Fri, 22 Feb 2013 17:23:21 -0500
Message-ID: <>

I'll still say, it depends.
MAA recommends to have high redundancy configured for the disks so that you can still have two copies of the data if you take a cell down for patching. Therefore, if you configure your disks for high redundancy, take the total of storage capacity and divide by 3. That is approximately how much storage you have available. So if you did high redundancy and the performance drives, your capacity is really reduced.

Here at the University of Michigan we decided to go with high capacity drives. Since we are consolidating our environments and have multi-terabyte databases, we chose capacity over performance. And we configured for normal redundancy.

Since we have not launched anything into production yet, I cannot tell you if it made a difference. But I have compared programs running in current production and on the Exadata machine and there was a marked difference in IO performance. Just confirmed how slow current IO architecture is and how fast striping and mirroring can be. We are currently RAID-5 plus metro-mirror copying as a DR solution.

For what it is worth!

Carol Dacko
University of Michigan

On Fri, Feb 22, 2013 at 3:47 PM, Stephens, Chris <>wrote:

> After reading through a decent amount of information on Kevin Closson's
> site, it seems pretty convincing that there is a mismatch between the
> ability of Exadata's compute nodes to process data at the same rate that
> the storage nodes can serve up. Obviously that is somewhat dependent on
> individual workloads.
> Given that, are sites tending to go with the high capacity drives in the
> storage nodes?
> I know that is a very general question that might get a lot of 'it
> depends' answers but I'm trying to figure out how to decide between the two
> without actually knowing what the workload is going to be. I'm just being
> asked to make a best guess at this point.
> Thanks for any comments.
> Chris
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Received on Fri Feb 22 2013 - 23:23:21 CET

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