Re: asm disks

From: Radoulov, Dimitre <>
Date: Mon, 04 Feb 2013 22:11:07 +0100
Message-ID: <>

On 02/04/2013 09:37 PM, Mike Hayes wrote: [...]
> He was all about
> that ASM was the way to go and to not use hardware raid and just let ASM do
> everything for you was best practice. Now I start reading the Storage
> Administrators guide and come across the following in chapter 2:
> Logical unit numbers (LUNs)—Using hardware RAID functionality to create
> LUNs is a recommended approach. Storage hardware RAID 0+1 or RAID5, and
> other RAID configurations, can be provided to ASM as ASM disks.
> e
> It seems to me we have just gone against best practice. For those who have
> experience with ASM do you use hardware raid or not?

I believe that in _most cases_ HW raid is the preferred way. Additional references:

VLDB and Partitioning Guide states the following:

With Oracle ASM mirroring, the mirror is produced by the database servers. Consequently, write operations require more I/O throughput when using Oracle ASM mirroring compared to using hardware-based mirroring.

Automatic Storage Management Administrator's Guide, Recommendations for Storage Preparation:

Create external redundancy disk groups when using high-end storage arrays. High-end storage arrays generally provide hardware RAID protection. Use Oracle ASM mirroring redundancy when not using hardware RAID, or when you need host-based volume management functionality, such as mirroring across storage systems. You can use Oracle ASM mirroring in configurations when mirroring between geographically-separated sites (extended clusters).

So ASM redundancy could be usefull when defining one failure group per disk arrayas
(mirror across storage arrays) and for stretched clusters.


Received on Mon Feb 04 2013 - 22:11:07 CET

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