Re: Migrate from AIX to Linux

From: Deepak Sharma <"Deepak>
Date: Mon, 22 Feb 2016 19:42:04 +0000
Message-ID: <433710192.8598179.1456170123969.JavaMail.yahoo_at_mail.yahoo.com>



In preparation for the migration from AIX to Linux, we are starting to look into tools to compare performance between the two environments. To recap, this is a 170TB DB, generating 5TB archive a day (even after a lot of operations as nologging). What are some 'low-cost good-quality' tools that you can recommend (or have an experience with), to compare performance before we cut-over to Linux? The Oracle's Real Application testing (RAT) is an option but could be very expensive. I have also read about BenchMark factory, HammerOra, JMeter, SwingBench and SLOB.  Any thoughts? Thanks,Deepak

    On Thursday, December 17, 2015 3:08 PM, Andrew Kerber <andrew.kerber_at_gmail.com> wrote:  

 asynch and direct io.  If there is some reason why you do not want to use ASM, use filesystemIO_options=setall in the init.ora.

On Thu, Dec 17, 2015 at 3:00 PM, Dimensional DBA <dimensional.dba_at_comcast.net> wrote:

CIO is redundant to Oracle overall I/O and caching mechanisms. You should use Oracle ASM on Linux.  Matthew ParkerChief Technologist425-891-7934 (cell)Dimensional.dba_at_comcast.netView Matthew Parker's profile on LinkedIn From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Deepak Sharma (Redacted sender "sharmakdeep_oracle" for DMARC) Sent: Thursday, December 17, 2015 12:35 PM To: andrew.kerber_at_gmail.com; gogala.mladen_at_gmail.com; oracle.blog3_at_gmail.com Cc: oracle-l_at_freelists.org
Subject: Re: Migrate from AIX to Linux We are still ways out before we implement the solution (several months), but will definitely keep posted. I had a kind of related question w.r.t. AIX vs Redhat Linux.  Currently we use CIO with AIX. Is there anything equivalent on Linux (that doesn't involve ASM)? On Thursday, December 17, 2015 12:48 PM, Andrew Kerber <andrew.kerber_at_gmail.com> wrote: I am interested to hear how it goes, and how many rehearsals you plan before the final go live. -----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mladen Gogala Sent: Thursday, December 17, 2015 12:17 PM To: Deepak Sharma; oracle.blog3_at_gmail.com Cc: oracle-l_at_freelists.org
Subject: Re: Migrate from AIX to Linux

On 12/17/2015 12:52 PM, Deepak Sharma wrote:
> Now, since you have experience with actually doing the migration, let
> me know if this would work (we will of course try it out soon too):
>
> 1. Copy the 'datafile copies' from source to destination staging area
This can be achieved with a minimal downtime, by shutting down the database and snapping LUNs which contain the database. That is equivalent to a cold backup, only two orders of magnitude faster. After the snapshot, the database can be restarted.

> 2. Run the 'convert from platform' RMAN command, to convert those
> datafile copies so they land in the real datafile locations

Mount the snapshot onto the target machines and run "rman convert" to real locations. Re-create the control file with the new file locations. Since the target is Linux RAC, those will most probably look like this: '+DATA/<db_unique_name>/datafiles/......'. Something like "vi"  with global string replace capability would be ideal for editing "create controlfile" statement.

> 3. Copy the subsequent 'Incrementals' from source to destination area

Everything else remains the same. And yes, I have done that.

> 4. Convert the Incrementals on destination to apply to real datafile
> (from Step 2).
> 5. Repeat 3 & 4, until you're almost caught up, and do a final 3 & 4
> with source tablespaces being read-only.
>
> Does this make sense? Pls share your thoughts.
Yes it does. However, few steps have been left out. I am not sure whether AIX db is single instance or RAC, but  you will need to add the undo tablespace for each instance and create as many redo threads as you have instances. Single-instance database has only a single active redo thread. You will also need to add instances to OCR by using srvctl add instance. Only when that is done, you will have a full fledged RAC database on Linux.

Also, be very careful when performing loads. Make sure that the same tables are only loaded from one machine. Good luck, may the force be with you. Regards

>
> -thanks
>

-- 
Mladen Gogala
Oracle DBA
http://mgogala.freehostia.com

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Andrew W. Kerber

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Received on Mon Feb 22 2016 - 20:42:04 CET

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