Re: ASM Host Mirroring

From: Martin Klier <>
Date: Thu, 27 Mar 2008 13:35:35 +0100
Message-ID: <>


Randy Johnson schrieb:
> Normal or High Redundancy - Mirroring Provided by ASM
> External Redundancy - Redundancy external to ASM (disk/san/host
> level)


> I believe that when "host" based mirroring is in use in relation to ASM
> that it means the host OS or hardware is performing the mirror function
> outside of ASM so ASM is not mirroring the disk in this case.
> -- Mark D Powell --

ASM normal redundancy or above _is_ host based mirroring, within ASM, as described above by Randy.

> *Subject:* ASM Host Mirroring
> Does anyone know how ASM does host based mirroring. For example we
> have two storage arrays with 10 metres distance, two failure groups
> are created, one per array. How does ASM mirror the extents?
> Network? Using the Cluster Interconnect? Or a seperate Network?

The basic mirroring happens by writing simultanously to SAN/NAS whenever possible.
For all necessary (inter-node) communications, the cluster interconnect of CRS is used, but the bandwidth consumption there it's rather low in my experience. I've never seen problems there, if the interconnect is suffient for the DB, it's enough for ASM by far.

Martin Klier

Usn's IT Blog for Linux, Oracle, Asterisk

Received on Thu Mar 27 2008 - 07:35:35 CDT

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