Re: db and storage snapshot - may be a little OFF-TOPIC
Date: Fri, 28 Jun 2013 11:37:07 -0700
Message-ID: <CADsdiQjxjkvjiuKdo18mr1ErTPXEGPkzsjgVdPj-C6gWWK-7wA_at_mail.gmail.com>
yes, was wondering as I read this if the snapshots were broken down into "extents" instead of datablocks.
Would be interesting to host the snapshots on ZFS or Delphix to see what the storage space is like.
I work at Delphix, and all we do is thin clone databases and I've never seen any of our customers come anywhere near hitting the size of the database. It's actually harder than it sounds. I was curious to see after your initial email if anyone knew of any tricks to scatter modifications across an entire database.
- Kyle Hailey http://dboptimizer.com
Follow us on:
<https://www.facebook.com/DelphixCorp><http://www.linkedin.com/pub/kyle-hailey/0/9ab/273/>
Learn about Delphix in the Wall Street
Journal<http://blogs.wsj.com/cio/2012/07/24/delphix-wants-to-virtualize-your-databases/>
On Fri, Jun 28, 2013 at 9:05 AM, Ryan January <rjjanuary_at_multiservice.com>wrote:
> It may also benefit to double check exactly how the snapshots are
> occurring and how space is allocated. I'm not familiar with that
> particular storage, however I've learned to not assume an even
> block-for-block allocation for snapshot changes.
>
> At the device level some systems use "extents" for lack of a better
> term. As an example; some Dell equalogic arrays break large files down
> into 1MB chunks. If a single block of that 1MB chunk changes, a full
> 1MB of space is allocated to the snapshot. Assuming an equal
> distribution of changes and an 8k block size it would theoretically only
> require a change in 1/128th of your total blocks before you reach full
> allocation.
>
>
> On 06/28/2013 10:36 AM, Wayne Smith wrote:
> > Having equal space taken by production files and snapshots doesn't mean
> > every block has changed (assuming you have more than one snapshot). Each
> > snapshot is kept intact. So if your database changes any 1/4 of itself
> for
> > each snapshot and you have 4 snapshots, you have equal production and
> > snapshot space usage (assuming no dedup/compression).
> > Cheers, Wayne
> >
> >
> > --
> > http://www.freelists.org/webpage/oracle-l
> >
> >
>
>
> --
>
>
> ------------------------------------------------------------------
> This email is intended solely for the use of the addressee and may
> contain information that is confidential, proprietary, or both.
> If you receive this email in error please immediately notify the
> sender and delete the email..
> ------------------------------------------------------------------
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Jun 28 2013 - 20:37:07 CEST