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Home -> Community -> Mailing Lists -> Oracle-L -> Re: I/O contention with external process reading the oracle logs (online redo logs)
Hello All
I just had a meeting today about replication.
The situations is: One master db that is currently replicated
(master to master synchronous replication) to a second DB.
Both machines are NT and the is a direct cable connection
between the network cards on both machines.
However, this solves the problem of machine failure but does not cover the full disaster recovery as both machines are in the same room. In case of fire both machines will be destroyed.
We are thinking about adding asynchronous replication to replicate the
changes
across wan to a remote site. The problem is that this will load the
production system and the network link (wan is expensive), as the system
generates during peek time 10MB of archive logs every 2-3 minutes.
I saw that some of you are using Quest Shareplex. Can you share your reasons, success stories etc? Benchmarks results will be very welcome.
TIA
Yechiel Adar
Mehish
----- Original Message -----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
Sent: Thursday, June 06, 2002 4:32 PM
(online redo logs)
NB_ RESENDING in plain text - sorry, Outlook keeps seinding in html no
matter what default i set!
Hi lists,
I am using Quest Shareplex product for Oracle to Oracle one way
replication. I have two systems (source and target) and two environments
(dev, demo). On system one, the environments are setup as schemas within
one oracle instance (therefore each schema will be a SOURCE in the
replication). My other system has each environment set up a separate Orace
Instances (therefore each instance will become a TARGET in the replication).
I am trying to configure 2 separate replication streams (ie so that each replication process is SEPARATE from the other - one for DEV and one for DEMO). I will accomplish this by setting up Shareplex to use mulitple processes.
HOWEVER, Quest technical support has told me that this will cause contention. However, I dont see why is would from an os/oracle point of view. Basically Shareplex has a process which reads the online redo logs......... tech support is suggesting that is there a two processes trying to access the same block in the logs that contention can occur. This does not make sense to me. Below is the blurb from techincal support when I questioned their initial repsonse:
I would find it HARD to believe that only ONE process can read a block at a time. If this were true, then OLTP system would FAIL miserably!
Anyone have any ideas/comments regarding the OS and Oracle interaction ....
I mean are not the logs at this pointa UNIX file? and can't multiple
processes read a single unix file without bringing the whole system to its
knees?
Also, I am NOT knocking the techincal support, but I believe that the
opinion was formulated on an incorrect assumption on the operating system
and Oracle.
Thoughts/comments?
Thanks in advance.
Hannah
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: INET: johanna.doran_at_sungard.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-LReceived on Sun Jun 09 2002 - 12:43:22 CDT
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also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Yechiel Adar INET: adar76_at_inter.net.il Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L
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