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Oracle and LUNs on VA7100

Daniel D.B. Shafer Sr.
Occasional Advisor

Oracle and LUNs on VA7100

I've read on several discusssion threads that it is wise to place each major Oracle data group on SEPARATE LUNs, i.e. Archive logs on one LUN, Indicies on another LUN. (We are very new to VA technology and HPUX, and are preparing configuration policies for the VA7100.) How do you target each Oracle data group to a specific LUN? Do you create a separate VG for each? But what I really don't understand is - why does it matter that redo logs and archive logs reside in different LUNS if any given LUN is striped across all physical disks?

Thanks!
7 REPLIES
Hai Nguyen_1
Honored Contributor

Re: Oracle and LUNs on VA7100

Daniel,

...it is wise to place each major Oracle data group on SEPARATE LUNs...

Yes, it is only true when each LUN is mapped to a physical disk (and it is much better if each disk again is connected to a different controller) so the I/O can be efficient. As for VA7100, you can forget about this concept since VA7100, by default, is an AUTORAID array which will try tom maximize the I/O performance for you.
For detailed info, you should read "HP surestore virtual arrays 7100 & 7400".

Hai
Yogeeraj_1
Honored Contributor

Re: Oracle and LUNs on VA7100

Hi,
Here is an issue raised on Oracle Metalink.

For oracle, i would recommend using Locally Managed Tablespaces in any cases. Create tablespaces with uniform extent sizes - e.g. 64K, 1M, 10M, etc according and create objects (classied as small, medium, large) accordingly in the tablespaces...

============================================================
From: JF Cote 25-Jan-02 19:56
Subject: SAN vs. Tablespace/Datafile

RDBMS Version: 9.0.1
Operating System and Version: HP-UX 11i
Error Number (if applicable):
Product (i.e. SQL*Loader, Import, etc.): none
Product Version:

SAN vs. Tablespace/Datafile

Hi,
I am currently migrating a 7.3.4 from hp-ux 10.20 to 9.0.1 to hp-ux 11i (with a san storage).
Actually, our tables are spread into different tablespaces, tablespaces are spread on different disks. Example: table 1 t1 is stored in tablespace A (ta) and table 2 t2 is stored in tablespace B tb. The ta & tb are stored on different disk to avoid contention.
Now we are going to install the db on a hp SAN (Va7100 with 6 disks in autoraid).
Questions: is there any benefit to keep the actual structure or should i merge all these tables in a single tablespace? Doing it, i will save a lot of spaces and the space management will be easier.

Any idea?

TIA,
JF Cote

--------------------------------------------------------------------------------

From: Bill Schott 25-Jan-02 20:08
Subject: Re : SAN vs. Tablespace/Datafile


With large SANs, I've adopted (and recommend) the small/medium/large concept in which objects are assigned based on their extent size, with 1 extent size per tablespace. Extra large objects, continue to get their own tablespaces.
Basically with SANs, you no longer use tablespaces to balance IO. But putting all in one causes trouble as well with fragmentation issues.
============================================================

Hope this helps!
Best Regards
Yogeeraj
No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)
Daniel D.B. Shafer Sr.
Occasional Advisor

Re: Oracle and LUNs on VA7100

Hai,

Are you saying that I can forget about the concept of placing Oracle data groups (indicies,redo logs, etc)on different VA LUNS (since I have no control over which spindles a LUN is mapped to)?

In other words, previous discussion threads on VA7100/Oracle issues where experts refer to placing Oracle data groups on different LUNS are bogus recommendations?
Hai Nguyen_1
Honored Contributor

Re: Oracle and LUNs on VA7100

...
Are you saying that I can forget about the concept of placing Oracle data groups (indicies,redo logs, etc)on different VA LUNS (since I have no control over which spindles a LUN is mapped to)?
...
Yes.

You can consult with HP support to be more convinced about this.

Hai
Jeanine Kone
Trusted Contributor

Re: Oracle and LUNs on VA7100

I was in the same type of situation as you are about a year ago. We switched from Alphas to HPs with the autoraid. As hard as it is to adjust to, it is true, you do not need to worry about where to place which data. You have no control over where the data is placed on disk. So, as ingrained in us as it is to separate our Oracle data, it does not matter with the VA7100.

Of course, I still created my different filesytems names and separate tablespaces, etc. - just to give me some sort of order.

Jeanine
Hai Nguyen_1
Honored Contributor

Re: Oracle and LUNs on VA7100

Some more info for you on VA7100. By default, the data on the array will be switched between RAID 0+1 (striping+mirroring) and RAID 5 Double Parity by the array.
Data are in RAID 0+1 when it is being referenced a lot (faster I/0 while still maintaining data redundancy) and in RAID 5 DP when they are not referenced (space saver+data redundancy). If you use this array solely for ORACLE, you can set this array to support only RAID 0+1 (refer to HP surestore command view sdm manual)

Hai
Daniel D.B. Shafer Sr.
Occasional Advisor

Re: Oracle and LUNs on VA7100

Thank you all!

It is a bit strange to be out of the "load balance by spindle" business, but it's actually quite wonderful if it really works well. But I had heard opposing advise and wanted to get it clarified!

Thanks again!