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Comparision between Oracle Data Guard VS VVR

Created: 10 Jun 2013 • Updated: 19 Jun 2013 | 1 comment
Zahid.Haseeb's picture
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Hello all

I need a comparision between VVR and Oracle Guard. Any TechNote/Document will be appriciated

Operating Systems:

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mikebounds's picture

I haven't seen a tech note, but there is a comparison I answered in one of your previous posts - https://www-secure.symantec.com/connect/forums/does-oracle-uses-data-guard-and-rac-must-vcs-and-vvr

which says:

Disadvantages of VVR:

VVR will replicate a lot more data than Data Guard, because VVR replicates Oracle redo logs + archive logs + redo segments + Oracle Datafiles, where as Data Guard just replicates redo and therefore VVR requires more (about 3 times more) bandwidth  

Advantages of VVR:

 

  1. VVR can replicate files too, like Oracle binaries and config files and any other applications that may be running on the server, so that you only need one replication solution, not one for replicating Oracle data (ODG) and a different replication product for replicating files.
  2. Better solution for providing Firedrill which is the abilty to to test DR site while primary site is still running.  In VVR you take a Space-optimised snapshot (Copy-On-Write) and mount this snapshot to test database, whilst replication continues, whereas in ODG I believe you have to suspend replication while you test the database at the DR site (hence comprimising how up-to-date DR site is during the Firedrill test).
  3. If you loose connection to DR site, then when connection is restored I believe ODG switches to shipping completes log files, rather than individual transactions, so if you were to loose primary site during the "catch-up" and you had only shipped a partial redo log file, then this is of no use, whereas with VVR, the backlog is replicated from the SQL continously.
  4. VVR is more robust.  If you do operations the wrong way round with ODG, you have to resync from scratch and last time I worked with ODG a couple of years ago, we had to resync 2 or 3 times.  It is pretty hard to get into situation with VVR where you have to resync from scratch and for example, if you loose primary and so takeover at secondary, then to restore old primary with VVR is very easy, but the Oracle guy I was working with could not figure out how to do the same recovery when using ODG.

Mike

 

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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