RE: Active/Active Site A/Site B using SRDF
- From: "Matthew Zito" <mzito@xxxxxxxxxxx>
- To: <ryan_gaffuri@xxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 3 Apr 2007 17:41:49 -0400
EMC SRDF does not support active/active with neither synchronous nor
asynchronous configurations. When you have an SRDF environment your R1s
(near side) are writeable while your R2s (the far side) are not.
If you want to do active/active sites, you can do a RAC stretch cluster
using either long distance Fibre channel (bleh) or iSCSI (much better),
or you can do things at an application level.
Matt
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From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
ryan_gaffuri@xxxxxxxxxxx
Sent: Tuesday, April 03, 2007 12:39 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Active/Active Site A/Site B using SRDF
The SAN/Systems Administrators claim its possibly to have a Site
A/Site B setup(at two locations). Use SRDF asynchronously to populate
and keep both sites active.
1. I don't think its possible to actually write to sides(2
different databases) and still maintain transaction control? So at a
minimum you write to just one site and then populate the secondary site.
2. If both sites are active and the population of the second
site is asynchronous that implies that the second site will be slightly
behind so if users query both sites then one user may get an inaccurate
picture of the database.
3. Is it possible to have active/active with a synchronous SRDF?
I would think that would affect performance. Since you can't end the
transaction until both sides are applied.
4. I would think the better solution is to havea primary and
failover with the load balancer having an exception handler so when Site
A goes down, failover to site B.
5. If you want to use both sites to query, then you are better
off identifying performance intensive queries such as reports and use
the secondary site as a reporting database(unless Site A goes down, then
site B handles everything)
Even with all this you still have a single point of failure at
your load balance since its the entry point or is there a way to
multiplex this?
This is long... not sure how to summarize this.
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