Re: Snapshot DB's in Exadata?

  • From: Frits Hoogland <frits.hoogland@xxxxxxxxx>
  • To: Aaron Leonard <aachleon@xxxxxxxxx>
  • Date: Fri, 14 Jan 2011 19:58:37 +0100

There is a strong case for snapshots. It also moderately easy if you have setup 
the environment to use them (snap, convert the snapped database to something 
which makes it identifyable, startup).
Have you considered that there is a probability that your system is 
underperforming because of all the snapshots? Not saying it is, just: have you 
checked? (physical io times)

I don't know your exact environment and needs, but also partial/tablespace PITR 
could be an option.

Frits Hoogland
mailto: frits.hoogland@xxxxxxxxx
cell: +31-6-53569942

On Jan 14, 2011, at 6:39 PM, Aaron Leonard wrote:

> Thanks Frits.  I've considered flashback.  My concerns with it are 
> performance-related.  I can't imagine that querying through months of 
> flashback logs will satisfy performance needs.  Thoughts?
> It ~may~ be realistic to convert the few snapshots which live for months from 
> snapshots to clones.  If I could do that, I'd only need to query through a 
> week's worth of flashback logs.  The extra space needs could make justifying 
> Exadata more difficult.  This is the probably my best option at the moment 
> though...
> On Fri, Jan 14, 2011 at 4:30 AM, Frits Hoogland <frits.hoogland@xxxxxxxxx> 
> wrote:
> as always, it depends on what you exactly need.
> as has been said, there is no equivalence of storage snapshots. this means 
> you simply can't move the databases over to an exadata and follow the exact 
> same procedure's.
> however, there is oracle technology which might give the same resolution in a 
> different way. If you want to query the database at different points in time, 
> oracle's flashback technology might be the thing you are looking for.
> Frits Hoogland
> mailto: frits.hoogland@xxxxxxxxx
> cell: +31-6-53569942
> On Jan 13, 2011, at 9:12 PM, Aaron Leonard wrote:
>> Good afternoon.
>> I'm looking for looking for some advice from those familiar with Exadata.  
>> We're currently evaluating a move to Exadata, but our business processes 
>> require near-instantaneous snapshot functionality that I don't know if an 
>> Exadata system can provide.
>> On various schedules, we take snapshots (EMC storage), mount them r/w to 
>> different mountpoints and startup Oracle instances on those.  The point is 
>> to have fast, point-in-time views of our data, which can be modified and 
>> reported on for an extended period of time.  At any one time, we have up to 
>> 20 different snapshot databases running.   Some are retained up to 3 months 
>> before we recreated them from a new snapshot.
>> My struggle with giving a thumbs up on Exadata do I make this 
>> happen in Exadata?  Changing the existing business processes really isn't an 
>> option without significant work (possibly years worth) and having to do that 
>> really takes away Exadata's appeal.  Creating true clones would 
>> significantly slow down our overall batch process workflow and negate the 
>> justification (which is speeding up that workflow) for moving to Exadata.  
>> What are my options, if any?  I guess my hope is that Exadata has some 
>> undocumented functionality internal to it that does this...  Realistically, 
>> it probably does not, but since I can't just download one of these and test 
>> it out, I have to ask.  Any thoughts?  Some insight would be greatly 
>> appreciated.
>> Thanks,
>> Aaron

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