RE: Active/Passive "high availability"
- From: "Kerber, Andrew W." <Andrew.Kerber@xxxxxxx>
- To: kevinc@xxxxxxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Fri, 13 Apr 2007 14:37:38 -0500
IN rac, while technically you have one database, you should have at
least two instances of that database (one per server), and assuming you
do not share your oracle home, you also have multiple oracle
installations, etc. If your disks are properly mirrored onto separate
storage devices, you also have redundancy at the datafile level
(including the system tablespace). You just have to set it up correctly
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Closson
Sent: Friday, April 13, 2007 2:06 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: Active/Passive "high availability"
"Oracle RAC provides very high availability for applications by removing
the single point
of failure with a single server. If a node in the cluster fails, the
Oracle Database
continues running on the remaining nodes. Individual nodes can be
shutdown for
maintenance while application users continue to work."
...this claim is correct (barring bugs).
So, it seems to come down to how you define a "single point". If you
look at the "database" as a single point, then yes there is a SPOF, but
if you look at it more granularly and consider that the database resides
on hardware with mirrored disks and multiple controllers, fibre
channels, fans, power supplies, etc. - then there isn't really a SPOF at
the database level either because it would really require multiple
failures to bring down the database.
...this point is incorrect. You only have one system tablespace. That is
usually the wart that we point out.
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