active/active or active/passive ?

[Hein van den Heuvel]

Bob wrote>> There are alternative readings of the question.

I beg to differ. The first question "Currently the MSA1000 is setup as active/passive but I'm not sure this is best for my application."

The Active/Passive is just a controller setup choice.
Whether the OS/application can exploit Active/Active is an separate question.
With the indication that this is an Itanium, I'm assuming it is running OpenVMS 8.3 which works well with Active/Active.

The second question is whether there is a benefit of operating as a real cluster with concurrent access from more than one node.
That is heavily application dependent and one may just have to try.
But many an RDB case study has been done which may help decide without trying. Some folks clone database (tables) to get a read-only copy to report from (from multiple nodes as need be).

The third question is whether "I wonder if active/active will increase performance and allow both servers access to the same clustered raid. "
That is an ill formed and bad question suggesting that our nameless friend "MSA1000 advice" has some reading up to do to grasps the basics involved.
active/active has the POTENTIAL to incread performance, if that performance is defined by actual IO... but often the LOCKS define the performance. Active/Active versus Active/Passive should have nothing to do with whether two servers can see the same LUN (where LUN is a raid device defined on the MSA, exposed to a connection)

hth,
Hein

[John Gillings]

Sorry,

I misunderstood the question, assuming "active" and "passive" in the more general sense, rather than just about the storage controller.

Having active/passive storage configuration makes no sense for an OpenVMS cluster. That's only needed for operating systems that can't coordinate access between systems sharing the storage.

Once you've got the storage set to active/active, you then have to decide if it also makes sense for the application.

[Uwe Zessin]

> That's only needed for operating systems that can't coordinate access between systems sharing the storage.

John, that is completely wrong.

It has nothing to do with the operating system and whether it supports shared file systems. Windows and Linux work fine with active/active arrays, can do round-robin or other load balancing methods across multiple paths and at least Windows can deal with ALUA presentations if the vendor-supplied DSM (the storage-array Device Specific Module) is properly implemented.

In the past the majority of mid-range storage arrays did do an active/passive LUN presentation (without going too much into detail, but it does not necessarily mean that the send controller 'does nothing'). Examples for "active/passive" arrays are the old DIGITAL HSG60/80 or the DIGITAL/Compaq EVA-3000/5000 running firmware below V4.