FAQ
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

http://fritshoogland.wordpress.com
mailto: frits.hoogland_at_gmail.com
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 is....how 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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  • Aaron Leonard at Jan 14, 2011 at 8:14 pm
    I wouldn't say it is underperforming because we expect the primary and
    snapshot db's to share IO.

    Outside of the sharing of IO's in general, the snapshot db's are fast. That
    wasn't always the case, of course. We have some tables on SSD, so after the
    intial writes against those tables would happen, further reads against those
    tables would be against our reserve lun pool (made up of FC disks). Our
    reserve lun pool is now made up of SSDs to combat that problem.

    On Fri, Jan 14, 2011 at 12:58 PM, Frits Hoogland
    wrote:
    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

    http://fritshoogland.wordpress.com
    mailto: frits.hoogland_at_gmail.com
    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 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

    http://fritshoogland.wordpress.com
    mailto: frits.hoogland_at_gmail.com
    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 is....how 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

    --
    http://www.freelists.org/webpage/oracle-l

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