MSL2024 and DPM question

[BrianDoyle]

DPM server has dual port HBA going to 2 fabrics. Library has a single drive and dual library ports to both fabrics.

With one library port cabled, it works fine but to cable both library ports, DPM identifies the same device twice.

HP MPIO software installed but we had to disable the MPIO services and reboot to get it back to having just one port working.

Can DPM handle a dual path library?

If it can, how might i fix this?

[Sivaramakrishna_1 · Accepted solution]

Hi,

MPIO to Load balance the IO to Storage Arrays and not Tape Devices.

As far as i know you can't have load balancing on the different paths of MSL Library

More over, you should not connect the Both the ports of MSL libary, there is a advisory for this.

Below is some of advisories:
Information

Cabling Port B on Tape drives of MSL G3 Libraries can cause undesirable impact on the devices attached to SAN.

Details

As a best practice specified in EBS Design Guide it is recommended to avoid cabling port B of the tape drive.

EBS Design Guide available at www.hp.com/go/ebs.


one more:

Issue

For LTO fibre drives, there are 2 fibre ports. At the time of this writing, connection to both ports into a SAN is not supported. There is no fail over capability at this time from a hardware stand point. Some backup applications do support dual pathing and along with some operating systems but HP does not support it due to problems if the non active port is accessed during operations to the active port, it will cause failure of activity on active port.

Solution

Do not connect both fibre ports of LTO drives to a SAN. This is true for ESLe and EML tape libraries and MSL G3 and 1/8 G2 autoloaders with LTO4 fibre drives.

NOTE: LTO2 and 3 fibre drives in ESLe and EML libraries connect directly to an internal IFC in these libraries and not directly into the SAN. Only one port for these drives should also be connected to the IFC.

Hope this clarifie.

[Curtis Ballard]

Some of the information posted above is out of date and that response is misleading.

Both ports may be configured but IF AND ONLY IF you have either an application that supports multi-path tape (such as Data Protector) or you use fibre channel zoning to disable one of the ports from reaching the host.

The fibre channel zoning method is a sort of "poor man's" failover. If you lose a link you can reconfigure your zoning from a remote location to enable the second path until you can get the first one fixed.

DPM does not support multiple paths to a tape drive.

[BrianDoyle]

thanks for the update Curtis