Re: Upgrading Oracle cluster 11gR2 on Solaris
- From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 22 Jan 2016 02:11:41 -0500
On 01/20/2016 05:12 PM, Ali Alizadeh wrote:
Hello
We are planning to upgrade our oracle cluster 11.2.0.3 using raw
device (no ASM) to oracle GI 12c/ASM.
What will be the best approached to minimize the downtime?
Regards,
Ali
Well, if you have to upgrade on the same machine, then you don't have
any choice: since 12c doesn't support raw devices. you will have to
reformat them and put them into an ASM. That is a looong downtime
because that generally means expdp/impdp.
However, if you can get yourself a new set of machines, then the
procedure is much simpler:
* Create Grid infrastructure 12c and create a single instance 11G
standby on that box.
* Install Oracle 12c on one of the new boxes (software only).
* Fail over the to the standby. The downtime begins.
* Upgrade newly minted 11G database to 12c using DBUA.
* Make the new database into a RAC: you should already have UNDO
tablespaces and redo threads, just configure the instances and add
them OCR using srvctl add instance -i <SID> ....
* Bring the newly minted 12c RAC up. Downtime ends. The duration of
downtime depends on how long does it take to convert the DB and how
fast you can make it RAC. You can make several attempts, because
breaking the link between the primary and standby doesn't
necessarily mean downtime. If your infrastructure is good (10GB LAN
or better), you can relatively easy create standby database from the
live database.
However, cost of the downtime in the era of the Internet and web based
economy can be exorbitant. I am sure that your employer will gladly buy
relatively cheap generic hardware and avoid potentially devastating
downtime. I know of a case where downtime was measured as $100.000 per
hour. For large companies like Netflix, Amazon, Ebay, Paypal, banks with
on-line banking and stores like Walmart, the cost of total downtime is
probably much higher than that. And $100.000 can buy a lot of generic PC
hardware.
--
Mladen Gogala
Oracle DBA
http://mgogala.freehostia.com
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