Re: Oracle High Availability Question(s)

From: Stefan Knecht <knecht.stefan_at_gmail.com>
Date: Thu, 15 Feb 2018 10:12:28 +0700
Message-ID: <CAP50yQ8yvJ=DnE6sCtBOO52LmVS-B=SWj3GwZZOZ3nGg-4vAFQ_at_mail.gmail.com>

Small correction, seems I have been bit by the copy/paste bug:

SALES= (DESCRIPTION_LIST= (LOAD_BALANCE=off)  (FAILOVER=on)
 (DESCRIPTION= (CONNECT_TIMEOUT=5)(TRANSPORT_CONNECT_TIMEOUT=3)(RETRY_COUNT=3)

(ADDRESS_LIST= (LOAD_BALANCE=on)
(ADDRESS=(PROTOCOL=TCP)(HOST=Austin-scan)(PORT=1521)))
(CONNECT_DATA=(SERVICE_NAME=oltpworkload))) (DESCRIPTION=
(CONNECT_TIMEOUT=5)(TRANSPORT_CONNECT_TIMEOUT=3)(RETRY_COUNT=3)
(ADDRESS_LIST= (LOAD_BALANCE=on) (ADDRESS=(PROTOCOL=TCP)(HOST=

Houston-scan)(PORT=1521))) (CONNECT_DATA=(SERVICE_NAME=oltpworkload))) )

That extra "12" that snuck in there in my original mail shouldn't be there.

On Thu, Feb 15, 2018 at 10:10 AM, Stefan Knecht <knecht.stefan_at_gmail.com> wrote:

> There's lots of information out there on how to make use of Data Guard.
> Particularly Oracle's "MAA" - Maximum Availability Architecture -
> initiative has resulted in some great documents:
>
> http://www.oracle.com/technetwork/database/availability/oracle-database-
> maa-best-practices-155386.html
>
> For your particular case, you can take a look at this document:
> http://www.oracle.com/technetwork/database/features/availability/maa-wp-
> 11gr2-client-failover-173305.pdf which documents in a very detailed
> fashion how to configure your Oracle net stack to have painless switchovers
> or failovers.
>
> The key is using a TNS alias that includes both the primary and standby,
> based on a service that is tied to the database role (e.g. if the database
> currently is the primary, the service is active, otherwise it is not).
>
> Like this for example:
>
> SALES= (DESCRIPTION_LIST= 12 (LOAD_BALANCE=off)
> (FAILOVER=on)
> (DESCRIPTION= (CONNECT_TIMEOUT=5)(TRANSPORT_CONNECT_TIMEOUT=3)(RETRY_COUNT=3)
> (ADDRESS_LIST= (LOAD_BALANCE=on) (ADDRESS=(PROTOCOL=TCP)(HOST=Austin-scan)(PORT=1521)))
> (CONNECT_DATA=(SERVICE_NAME=oltpworkload))) (DESCRIPTION=
> (CONNECT_TIMEOUT=5)(TRANSPORT_CONNECT_TIMEOUT=3)(RETRY_COUNT=3)
> (ADDRESS_LIST= (LOAD_BALANCE=on) (ADDRESS=(PROTOCOL=TCP)(HOST=
> Houston-scan)(PORT=1521))) (CONNECT_DATA=(SERVICE_NAME=oltpworkload)))
> )
>
> As you can see, the single alias "SALES" includes both locations "Austin"
> and "Houston" and references them with the same service. That service is
> configured with a role-dependency and is only ever going to be active on
> the primary (whereever it may be).
>
> If you use active data guard, you can also do the same thing with a
> read-only reporting service. Just assign that to be only active on standby
> roles.
>
> You'd want to list the "intended" primary location, if there is one, in
> the first position to reduce the time it takes to connect.
>
>
> Stefan
>
>
>
> On Thu, Feb 15, 2018 at 3:39 AM, Scott Canaan <srcdco_at_rit.edu> wrote:
>
>> We are currently using Data Guard and we hate it. It’s the only place we
>> use it and we were never given any training on it, so we threw it together
>> as best we could. Every time we have to do anything with it (including
>> patching), we pray that it will recover and continue working.
>>
>>
>>
>> What we have proposed is to go to Linux clustering instead, eventually
>> going to Libvert, eliminating the Data Guard and moving the fault tolerance
>> to the cluster. The app is not Data Guard aware, so when a failover does
>> occur, the app stops working until someone manually points it to the other
>> server and restarts it. Linux clustering would solve that problem.
>>
>>
>>
>> RAC was mentioned as another alternative, so I’ve been looking into it,
>> but everything I found showed all of the nodes pointing to one disk or disk
>> array, which is not what we want. I’ve already said that if they want us
>> to go with RAC, we will require training as we are not going to go into it
>> blind like we did with Data Guard.
>>
>>
>>
>> Scott Canaan ’88 (srcdco_at_rit.edu)
>>
>> (585) 475-7886 – work (585) 339-8659 – cell
>>
>> “Life is like a sewer, what you get out of it depends on what you put
>> into it.” – Tom Lehrer
>>
>>
>>
>> *From:* oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freeli
>> sts.org] *On Behalf Of *Tim Gorman
>> *Sent:* Wednesday, February 14, 2018 3:27 PM
>> *To:* fuzzy.graybeard_at_gmail.com; oracle-l_at_freelists.org
>> *Subject:* Re: Oracle High Availability Question(s)
>>
>>
>>
>> Whether you have RAC licensing or not, anyone is far better off deploying
>> Data Guard for high availability.
>>
>> Data Guard is designed for high-availability and disaster-recovery first
>> and foremost. RAC is designed as a scalability solution first and
>> foremost, and the only way Oracle gets away with marketing it as an
>> availability solution is because RAC must include fault tolerance against
>> node failure to even operate. RAC is wonderful and mature software, but
>> using it for availability is an adaptation.
>>
>>
>> On 2/14/18 12:10, Hans Forbrich wrote:
>>
>> You might want to look up 'stretch RAC'
>>
>> One useful article is Oracle's wwhite paper
>> http://www.oracle.com/technetwork/products/clustering/
>> overview/extendedracversion11-435972.pdf
>>
>> disclaimer: My opinion, not my employer's
>> /Hans
>>
>> On 2018-02-14 11:59 AM, Scott Canaan wrote:
>>
>> Currently, we don’t have a license for RAC, therefore we aren’t using
>> it. We have one application in particular that is required to be available
>> as close to 7 x 24 x 365 as possible. One other requirement is that the
>> redundancy includes physical disk, with one set of disks in one location
>> and the redundant set in another location. In looking at RAC, it appears
>> that a shared disk (or disk group) is used which doesn’t satisfy the second
>> requirement. So far, I have not found a description of RAC that shows it
>> using more than one disk / disk group for redundancy. What is the best way
>> to accomplish the second requirement?
>>
>>
>>
>
>
>
> --
> //
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Received on Thu Feb 15 2018 - 04:12:28 CET