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Oracle ASM and Multi-Pathing Technologies

Doc ID:  Note:294869.1

This document will briefly discuss Multipath I/O and how Oracle Automatic Storage Management leverages multi-pathing.

An I/O path generally consists of an initiator port, fabric port, target port, and LUN. Each permutation of this I/O path is considered an independent path. Dynamic Multi-pathing/failover tools aggregate these independent paths into a single logical path. This path virtualization provides I/O load-balancing across the HBAs, as well as non-disruptive failover on HBA failures. Multi-pathing software requires all the required disks to be visible on each available and eligible HBA. These multi-paths will be detected by probing the World Wide Device Identifiers (WWD ID).

Multi-pathing software also provides multi-path software drivers. Most multi-pathing drivers are SCSA compliant pseudo nexus drivers, that support multipath services for fibre channel attached SCSI-3 devices. These drivers receive naming and transport services from one or more physical HBA devices. To support multi-pathing, a physical HBA driver must comply with the multi-pathing services provided by this driver.

Multipaths provides the following benefits:

Provide a single block device interface for a multi-pathed LUN

Detect any component failures in the I/O path; e.g., fabric port, channel adapter, or HBA.

When a loss of path occurs, ensure that I/Os are re-routed to the available paths, with no process disruption.

Reconfigure the multipaths automatically when events occur.

Ensure that failed paths get revalidated as soon as possible.

Provide auto-failback capabilities.

Configure the multipaths to maximize performance using various load balancing methods; e.g., round-robin, least I/Os queued, or least service time.

Examples of multi-pathing software include EMC PowerPath, Sun Traffic Manager and IBM MPIO.

Although most of these tools are storage array agnostic, some require additional software components and drivers specific for the storage

Note, Oracle Corporation does not certify or qualify these tools. Oracle10g includes a new feature called Automatic Storage Management (ASM). ASM provides filesystem and volume manager capabilities built into the Oracle database kernel. With this capability, ASM simplifies storage management tasks, such as creating/laying out databases and disk management. Although ASM does not provide multi-pathing capabilities, ASM does leverage multi-pathing tools, as long the path or device produces a successful return code from an fstat system call.

The table below describes the attributes of the utilities and how it can be used by ASM.

Note, that Oracle Corporation does not certify ASM against these multipathing utilities. The MP utilities listed below are ones that known working solutions. As we do more testing, additional MP utilities will be listed here, thus, this document is an active document.

由于粘贴过来表格格式有问题，按照下面的格式粘贴

OS Platform

Multi-pathing tool

ASM Device Usage

Notes

1)AIX 系统

多路径软件EMC PowerPath

Use raw partitions thru

the pseudo device /dev/rhdiskpowerx

多路径软件IBM SDD (Vpath)

As of this writing, SDD-AIX is known to cause discovery and device handling problems for ASM, and thus is not viable solution.

See SDDPCM section below for an alternative solution to SDD for AIX

多路径软件IBM SDDPCM

Use /dev/rhdiskx device

You m ust install SDDPCM filesets and enable SDDPCM.. SDDPCM cannot co-exist w/ SDD.

SDDPCM only works with the following IBM storage components:

DS8000,DS6000,Enterprise Storage Server (ESS)

多路径软件Hitachi Dynamic Link Manager - HDLM

Use /dev/rdsk/cxtydz that’s generated by HDLM

HDLM generates a scsi (cxtydzx) address where the controller is highest unused controller number.

HDLM no longer requires HACMP.

多路径软件Fujitsu ETERNUS GR Multipath Driver

Use /dev/rhdisk device

2)HP 系统

多路径软件EMC PowerPath

ASM can use the raw partitions. Must use native device path:

/dev/rdsk/cxtydz

多路径软件HP SecurePath

ASM can use the raw partitions.

/dev/rdsk/cxtydz. Since Securepath doesn’t support pseudo-paths, use a single path for any given disk

多路径软件Hitachi Dynamic Link Manager – HDLM

Use /dev/rdsk/cHtydz that’s generated by HDLM

HDLM generates a scsi address like cHtydz.

多路径软件Sun Traffic Manager

ASM can use the pseudo device.

The pseudo device will have the Global Unique Identifier included its name.

3)Sun 系统

多路径软件PowerPath

ASM will use raw partitions, associated with the pseudo device:

/dev/rdsk/emcpowerx多路径软件Sun Traffic Manager

ASM can use the pseudo device.

The pseudo device will have the Global Unique Identifier included its name.

多路径软件Hitachi Dynamic Link Manager - HDLM

Use /dev/rdsk/cxtydz that’s generated by HDLM

HDLM generates a scsi (cxtydzx) address where the controller is highest unused controller number.

多路径软件Fujitsu ETERNUS GR Multipath Driver

Use /dev/FJSVmplb/[r]dsk/mplbI*1s{0-7}. *1 "I" is MPLB Instance number

4)Linux 系统

多路径软件IBM-SDD

ASM can use the raw device associated with the Vpath.

You must use SDD-Linux driver 1.6.05+ . Goto IBM SDD site to get latest driver

SDD works with the following IBM storage components:

DS8000

DS6000

Enterprise Storage Server (ESS)

SAN Volume Controller (SVC)

多路径软件PowerPath

ASM can use raw partitions associated with the /dev/emcpowerx device.

Associate the raw devices with the PP device.

多路径软件HP SecurePath

ASM should use raw devices associated with /dev/spx

Currently SecurePath is only available on x86 and Itanium, all other 64bit platforms are not supported

多路径软件MD

ASM can use raw device associated with /dev/mdx device.

Though not a real multipath solution, it does provide rudimentary active/passive support

多路径软件Device Mapper (DM)

ASM can use the name generated by DM:

/dev/disk/by-name/WWID

Avail in 2.6 kernel. Refer to following note for specifics

多路径软件Hitachi Dynamic Link Manager - HDLM

Use /dev/rdsk/cxtydz that’s generated by HDLM

HDLM generates a scsi (cxtydzx) address where the controller is highest unused controller number.

多路径软件 Fujitsu ETERNUS GR Multipath Driver

Associate raw device to /dev/FJSVmplb/[r]dsk/mplbI*1s{0-7}