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 Post subject: Oracle database disk layout on 3PAR
PostPosted: Mon Sep 11, 2017 7:36 am 

Joined: Tue Jun 13, 2017 2:57 am
Posts: 19
Hi,

We are currently installing Oracle database servers (RHEL 7) connected to a 3PAR 8400(4N) AFA.

Historically on EVA for a 1Tb Oracle database we created :

    10 * 100Gb for Data
    2 * 10Gb for redo logs
    4 * 25Gb for archived logs

This was done to split the vLUNs between the 2 controllers.

On 3PAR we hesitate between 2 disk layouts :

    1 * 1.2Tb for Data, redo logs and archived logs
--> easy for management, ...

OR

    1 * 1Tb for Data
    2 * 10Gb for redo logs
    1 * 100Gb for archived logs

Oracle recommendation is to put the redo logs on separate disks but is it always needed/advised with a 3PAR where the Virtual Volumes are spread on all the physical disks ?

Kind regards,

Morbid


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Mon Sep 11, 2017 8:38 am 

Joined: Wed Nov 19, 2014 5:14 am
Posts: 505
It's not really about wide striping, EVA had that too at least at the backend, the reason for separation is to provide the ability to recover and roll forward if there's a failure / corruption. More volumes for the database typically means a higher overall queue depth meaning data can queued in parallel and so provide better random performance. Smaller volumes handled by a volume manager also help with expansion etc.

Also many backup and snapshot integrations will expect the logs to also reside on separate volumes, I believe HPE stopped producing application specific best practice guides a while back, but there's a WP here that might give some more insight.

https://h20195.www2.hpe.com/V2/GetDocument.aspx?docname=4AA6-6275ENW


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Tue Sep 12, 2017 7:46 pm 
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Joined: Tue Aug 18, 2009 10:35 pm
Posts: 1328
Location: Dallas, Texas
Morbid wrote:
Oracle recommendation is to put the redo logs on separate disks but is it always needed/advised with a 3PAR where the Virtual Volumes are spread on all the physical disks ?

Kind regards,

Morbid



Excellent question! The answer is to keep them on separate virtual volumes but don't meddle with the backend CPG disk layout by attempting to divide physical disks up into different cpgs for logs/data/index etc.

Keep your DBAs happy, let them have the LUN layout they are comfortable with, and more importantly, what Oracle support is comfortable with.

Each VV (LUN) still has OS limits on outstanding queued IO depth.... more luns, more parallel IO queues. That said I would recommend At least 2 luns for Data and Indexes (or 2 luns for ASM to manage) and luns for redo logs, and the separate luns for archive logs.

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Richard Siemers
The views and opinions expressed are my own and do not necessarily reflect those of my employer.


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Mon Sep 18, 2017 10:35 am 

Joined: Mon Apr 28, 2014 4:51 pm
Posts: 38
Location: Rockford, MI
My two cents and a couple of things to note. My DBA's tell me, and is what I use to determine how to provision space, is that the max oracle data file size is 32GB, so each time they need to add space it will occur in 32GB chunks. As a best practice we create multiple database VV's and we keep them all the same size, if I grow one I grow them all for consistency and predictability. Here, we run Oracle on Windows so it's rather easy to add space without impact, it appears you are deploying on Red hat so if you add space to a VV it will be created as an extent which after time could introduce performance issues.

I would recommend working with your DBA's and agreeing on a max VV size, in my case we deploy in 1.5TB increments on our large servers, 500GB increments in our medium and 250GB on our smaller, this of course is barring the tiny one offs. We also start out with four DB LUNs on each server and it is up to them to round robin the creation of the data files. Since everything is thin provisioned I'm not wasting space and I'm ensuring that I can guarantee performance out of the gate.

Also, like you, we also dedicate LUNs to redo and achieve, however we only have a single LUN for archive, we have not seen a need to have multiple outside of our asynced copies.

I also came from the EVA world and I think you will be pleased with the performance you will receive by moving to 3PAR. If you haven't read it yet HPE published a technical whitepaper for EVA admins http://691d3755c7515ca23f7b-dbfc12bd0c567183709648093997d459.r57.cf1.rackcdn.com/assets/en/4aa4-3999enw-an-introduction-to-hp-3par-storeserve-for-eva-administrator-version-2.pdf

In the end I make it my business to work closely with my SQL, Oracle and SAP engineers and admins to collectively design tailored best practice implementations as our core business runs on these platforms.

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Adam Berus - I.S. Tech Lead - Wolverine Worldwide Inc.
x1-7200, x2-7400, x1-7450, x1-8400, x2-8440
3PAR Technologies: AFC, AO, FilePersona, RemoteCopy (RCIP)


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Mon Sep 18, 2017 11:54 am 

Joined: Tue Jun 13, 2017 2:57 am
Posts: 19
Hi,

Thanks for advices

We don't have big databases (max size is 1,2Tb) and we have a lot of small (50-100Gb)

DBA would like to keep it simple it's why we hesitate to make only one big lun per database ...

Snapshot is not a concern, we take daily full backup on storeonce without backup window problem.


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Tue Sep 19, 2017 3:15 am 

Joined: Thu Apr 20, 2017 6:23 am
Posts: 4
What I'm using is following layout , and performance is acceptable for application people

1 * 1Tb for Data -> We are using RAID5 or RAID6(preferred) CPG. Up to 16TB per LUN without performance problems.
2 * 10Gb for redo logs -> use RAID1 CPG
1 * 100Gb for archived logs -> use same RAID1 CPG as for redo logs

don't limit CPGs and let them do the wide stripping across all the drives.


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Tue Sep 19, 2017 11:37 am 

Joined: Tue Jun 13, 2017 2:57 am
Posts: 19
maslo64 wrote:
What I'm using is following layout , and performance is acceptable for application people

1 * 1Tb for Data -> We are using RAID5 or RAID6(preferred) CPG. Up to 16TB per LUN without performance problems.
2 * 10Gb for redo logs -> use RAID1 CPG
1 * 100Gb for archived logs -> use same RAID1 CPG as for redo logs

don't limit CPGs and let them do the wide stripping across all the drives.


Also for small databases < 50Gb ?


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 Post subject: Re: Oracle database disk layout on 3PAR
PostPosted: Wed Sep 20, 2017 12:55 am 

Joined: Thu Apr 20, 2017 6:23 am
Posts: 4
We have mix of large and small DBs and for consistency reasons we always create same setup. (also I don't have to argue with DB people about performance recommendations from Oracle)

If there are no mirror logs configured I would use 1xLUN RAID1 for redo logs.


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