topic Re: MSA1500 Controller in Disk Enclosures

MSA1500 Controller

Muhammad Farhan Nasir — Wed, 04 May 2011 12:28:54 GMT

Does an MSA1500 do true active/active performance? Fibre channel switch port traffic shows traffic only on one path to the MSA. MSA1500 reports:
Supported Redundancy Mode: Active/Standby Asym-Active/Active
Current Redundancy Mode: Asym-Active/Active.

but only one controller showing activity and second controller show on only Active LED on LED number "7".

is ther any problem in MSA controller or FW issue.

Re: MSA1500 Controller

Johan Guldmyr — Wed, 04 May 2011 13:12:13 GMT

asym - asymmetrical active/active - meaning one controller owns the LUN and if requests come in through the proxy-controller it forwards the request.

Maybe your hosts are so smart (have the ALUA sensing MPIO/multipating software) that they only speak to the owning controller?

Re: MSA1500 Controller

Torsten. — Wed, 04 May 2011 13:35:09 GMT

On active/passive configurations one controller owns all the LUNs, the other controller is just standby.

On active/active 1 controller owns a LUN and does the work, but the controller can own another LUN and do the work for this LUN.

Since passing over the data from the standby to the owner, the data should only be handled by the LUN owner (this is what you see).

But now it is a bit more complicated, since the disks are single pathed, the controllers have to "somehow" share the internal busses anyway.

Re: MSA1500 Controller

Torsten. — Wed, 04 May 2011 13:38:10 GMT

should be

On active/active 1 controller owns a LUN and does the work, but the other controller can own another LUN and do the work for this LUN.

Re: MSA1500 Controller

Muhammad Farhan Nasir — Wed, 04 May 2011 19:38:28 GMT

Thanks.
my all LUN Preferred Path is : "Controller 1"

possible to change LUN Preferred Path...

Re: MSA1500 Controller

Torsten. — Thu, 05 May 2011 08:36:57 GMT

The manual (worth to read!) says:

"Auto is the default setting for new configurations. In this case, the storage system automatically selects the I/O path from the redundant controller to the logical drive and dynamically load balances all paths."

But you can also set it manually to controller 1 or 2.

Re: MSA1500 Controller

Uwe Zessin — Thu, 05 May 2011 08:44:22 GMT

We need some more background information like what firmware is on the controllers (there was one code stream that was 'almost A/A' - it looked A/A, but run A/P)

and then what operating system and version is running on the hosts, because that defines how the multipath environment must be configured. The MSA might do 'automatic' round-robin assignment of logical disk ownership, but it can do ownership transfers like the EVA if too much host I/O goes through the non-owning controller.

Re: MSA1500 Controller

Muhammad Farhan Nasir — Thu, 05 May 2011 09:16:35 GMT

OS is HP-UX 11.23