Uses of Volume Replicator with Oracle 10g or 11g

[bpham]

We're looking at reducing our downtime windows for our Oracle environments.  Most of the downtime are required for Oracle patching, for both database more importantly Oracle Applications (ERP) patching and upgrades which sometimes takes a couple of days.  During this time, of course, the database is not available to users.

I have a few questions.

1.  Can we use VVR to replicate our PROD1 database to PROD2 and then before patching/upgrade:
     a.  Switch the database over to PROD2.
     b.  Allow users update access to PROD2.
     c.  Patch/upgrade PROD1.
     d.  When PROD1 is finished, sync PROD1 and PROD2.
     e.  Bring PROD1 back online for user access.

Of course, all updates to PROD2 and to PROD1 during PROD1's patching/upgrade will be there at the end in PROD1.

Can this be done (may be together with VCS)?  If not, then question 2 below.

2.  Can VVR replace Oracle DataGuard?  What are the benefits and drawbacks?  I've read some of the articles from Oracle about the benefits and drawbacks of both products, but I'd like to hear from people who have used VVR and VCS in an Oracle environment.

3.  What about VCS?  Can it replace Oracle RAC?  What are the pros and cons?

Also, can you point me to some documents/white papers that talks about using VVR and VCS to achieve 24x7 Oracle environment?

Thank you for any input.

[TomerG]

1. You can do this assuming that upgrading the PROD1 server is updating the binaries only (which of course are NOT in the RVG (e.g. on local disk). This can be done with or without VCS. Without VCS you'd use VVR's migrate function to change who the Primary is, temporarily.

2. Yes, VVR can replace DataGuard. Not sure the benefits and drawbacks in detail, I've only used VVR to replicate Oracle.

3. VCS (with Storage Foundation for Oracle RAC) can replace Oracle's CRS (Cluster Ready Services) and ASM (Automatic Storage Management). Main pros are that SF for Oracle RAC (which includes VCS) has been doing it longer, is written by engineers who know clustering foremost, and contains features like I/O Fencing which is amore bullet-proof split-brain prevention method than "quorum" features that are employed by the likes of Oracle CRS, Suncluster, etc. Also, VxFS with Oracle was the first file system to pioneer Quick I/O, which is effectively what Oracle later stated is ODM compliancy (i.e. file systems that allow for databases with raw disk performance), and has been doing this for over 10 years now.

Additionally, SF for Oracle RAC allows Oracle to use LLT and GAB to do cross-node communication (for Cache Fusion, etc) so performance may be increased over using TCP/IP, although I don't know that there is evidence to support this.