Windows Storage Server 2003, part 5

Now that you know all about the Virtual Disk Service (VDS) in Windows

Storage Server 2003, let's take an in-depth look at a technology called

Multipath I/O (MPIO).

MPIO allows you to have multiple paths to external storage components or

other NAS devices. Multipathing gives you the ability to build fully

redundant and persistent connections between storage devices and the

associated systems.

In actuality, MPIO is not a service provided by Windows Storage Server

2003, but more of a capability. To take advantage of this capability,

hardware vendors must develop the appropriate drivers using the Driver

Development Kit (DDK).

Microsoft's MPIO delivers a standard and interoperable path for

communication between storage products and Windows Server.

Additionally, multipathing allows a host to have up to a maximum of 32

paths to access an external storage device. This allows for hot

failover and load balancing between connections. Multipathing technology

is critical in ensuring highly available data to businesses.

If you are familiar with HP AutoPath or EMC PowerPath, then you are

already familiar with multipathing technology. Both HP and EMC have

developed multipathing drivers for their hardware such that you can

connect a Windows Storage Server 2003 NAS device to one of their

external NAS or SAN devices. This allows you the flexibility to grow

your systems in a customized manner, as well as grow into new

technologies while still leveraging existing investments in other

platforms and technologies.

By taking advantage of MPIO technology, you can have two fiber or

Ethernet gigabit controllers in your NAS device and have both of them

redundantly connected to an external storage device (such as your SAN).

With MPIO, one of these controllers can fail and the other one will

automatically take over the load, without any disruption to the


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