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Automatic Storage Management (ASM) vs Raid 5 [message #334849]

Fri, 18 July 2008 06:17

gmkhaw@yahoo.com
Messages: 14
Registered: September 2006
Location: Malaysia

Junior Member

I am going to install Oracle 10gR2 on IBM raid 5 server with some questions facing:
- Can ASM run on raid 5 configured server? How if possible?
- Will ASM slowdown the database performance?
- ASM recovery mechanism is auto from the mirror or manual?

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Re: Automatic Storage Management (ASM) vs Raid 5 [message #334891 is a reply to message #334849]

Fri, 18 July 2008 09:58

Mahesh Rajendran
Messages: 10707
Registered: March 2002
Location: oracleDocoVille

Senior Member
Account Moderator

>> Can ASM run on raid 5 configured server? How if possible?
Yes. Nothing special. Infact ASM and RAID levels are not related.
ASM is just a volume manager. Just choose your
optimum RAID level for your requirement.
For high I/O intensive databases, RAID-5 is not so good.
Do not keep redologs in RAID-5.
>>- Will ASM slowdown the database performance?
If anything is such obvious, why would Oracle recommend this feature?
It depend on how bad you have configured it and some possible internal bugs.

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Re: Automatic Storage Management (ASM) vs Raid 5 [message #334963 is a reply to message #334891]

Fri, 18 July 2008 21:48

gmkhaw@yahoo.com
Messages: 14
Registered: September 2006
Location: Malaysia

Junior Member

>I plan to install ASM with normal redundancy, but oracle expect/require each disk group to be in separate physical disks. Since RAID 5 can only configure the disk into logical drive and we can not identify the physical disk, will this affect the expected results?
> Why only redo logs can not keep in RAID 5?
> If redo logs can not keep in RAID 5, that means the ASM setting for these files need to be pointed to external disk in RAID 5 environment?

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Re: Automatic Storage Management (ASM) vs Raid 5 [message #334964 is a reply to message #334849]

Fri, 18 July 2008 22:17

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

> Why only redo logs can not keep in RAID 5?
It is "can not". It is should not.
Redo logs are VERY write intensive.
With RAID5 volume, when a data block is written, the XOR block must be written to the same volume to provide the redundancy.
This effectively doubles the I/O activity to the volume,
or halves the effective I/O operations to this volume.
RAID5 volumes are good where READ activities dominate.

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Re: Automatic Storage Management (ASM) vs Raid 5 [message #334967 is a reply to message #334964]

Fri, 18 July 2008 23:48

gmkhaw@yahoo.com
Messages: 14
Registered: September 2006
Location: Malaysia

Junior Member

> If redo logs should not place in RAID 5, what is the recommended setting? Don't use RAID 5?

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Re: Automatic Storage Management (ASM) vs Raid 5 [message #334970 is a reply to message #334849]

Sat, 19 July 2008 00:15

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

Better is RAID1, better still is RAID1+0 aka RAID10
or multiplex across individual drives which is equivalent to RAID1.

[Updated on: Sat, 19 July 2008 00:17] by Moderator

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