Re: asm disks
From: Radoulov, Dimitre <cichomitiko_at_gmail.com>
Date: Mon, 04 Feb 2013 22:11:07 +0100
Message-ID: <511023EB.9020208_at_gmail.com>
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?
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.
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).
Date: Mon, 04 Feb 2013 22:11:07 +0100
Message-ID: <511023EB.9020208_at_gmail.com>
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?
Hi,
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.
Regards
Dimitre
-- http://www.freelists.org/webpage/oracle-lReceived on Mon Feb 04 2013 - 22:11:07 CET