Secure Path for VA disk array ... do I need it?

[Jason Dinsdale]

Hi all,

Currently have a VA7110 attached in point-to-point FC fashion to an RP3440 HP-UX server with dual FC HBAs, one connected to each VA controller for redundancy and load-balancing. As it stands, I have 2 LUNS presented to the UNIX server, which appear with primary and alternate paths within LVM. I then stripe LVs accross the 2 LUN PVs to balance I/O accross HBAs and controllers.

The next phase of our SAN implementation is to introduce a 2 FC switch fabric (using 2/8V's) between the server and the disk array, with each HBA connecting to it's own FC switch. This will obviously change the hardware paths of the LUNs and presumably the device files also.

As I understand it, Secure Path masks the complexity of the redundant PV links under LVM and instead I'm presented with one LUN device file which I then use as a PV within LVM, and this would allow me to do away with the striping accross 2 PVs (LUNs) to do load balancing etc.

My question is ... do I really *need* Secure Path or is this optional? As far as I can work out, I could keep with my existing arrangement, although I would need to adjust the LVM config for the new hardware paths and therefore device files that represent them. Is that about it or is there something I'm missing?

Thanks,

Jason

[Slawomir Gora · Accepted solution]

Hi,

I think you are talking about Auto Path product
(Secure Path is for EVA).

In my opinion you don't need Auto Path - LVM is sufficient solution for HP-UX machine.

[Peter Mattei]

Jason

You can perfectly keep on using PVLINK as you are used to. This is active passive presentation of the individual LUNs. You can statically balance your LUNs to your paths.

The advantage of SecurePath is that both paths can be active and you can dynamically balance your IOs.
By the way AutoPath is now included in SecurePath for HP-UX and Windows.

Since you are using the VA7110 it does not make much sense to use loadbalancing. The VA7110 has one redundancy group which is owned by one controller. IOs coming through the other controller will be routed internally to the controller owning the redundancy group.
Therefor I would use PVLINK, configure all active paths to that active controller and only use the second controller for alterante paths.

Examples on how to configure your SAN can be found in the User and Service Guide here
http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?locale=en_US&contentType=SupportManual&docIndexId=1255&prodTypeId=12169&prodSeriesId=298817

Cheers
Peter

[Peter Mattei]

Jason

You can perfectly keep on using PVLINK as you are used to. This is active passive presentation of the individual LUNs. You can statically balance your LUNs to your paths.

The advantage of SecurePath is that both paths can be active and you can dynamically balance your IOs.

Since you are using the VA7110 it does not make much sense to use loadbalancing. The VA7110 has one redundancy group which is owned by one controller. IOs coming through the other controller will be routed internally to the controller owning the redundancy group.
Therefor I would use PVLINK, configure all active paths to that active controller and only use the second controller for alterante paths.

Examples on how to configure your SAN can be found in the User and Service Guide here
http://h20000.www2.hp.com/bizsupport/TechSupport/DocumentIndex.jsp?locale=en_US&contentType=SupportManual&docIndexId=1255&prodTypeId=12169&prodSeriesId=298817

Cheers
Peter

[Jason Dinsdale]

Gents,

Thanks for confirming my suspicions.

Jason