Active/Active backend paths

[GRANGARAJAN1]

I am currently using a NetApp v6280 cluster connected to a HDS storage system via a Fabric. How can I make all the backend paths to the storage system be Active/Active? Currently the system is treating them as Active/Passive and thus potentially using only half the paths. The V-series best practices guide points out this path information as well and I am wondering if there's a way to fix this?

v6280-top> storage array show-config

           LUN Group                    Array Name       Array Target Ports           Switch Port  Initiator

   Group 0 (18 LUNS)              HITACHI_DF600F_1  50:06:0e:80:10:13:8c:22      bs32_testbed1:29         0d

                                                                           50:06:0e:80:10:13:8c:2a      BS33_testbed2:23         0b

   Group 1 (22 LUNS)              HITACHI_DF600F_1  50:06:0e:80:10:13:8c:28      bs32_testbed1:31         0c

                                                                           50:06:0e:80:10:13:8c:20      BS33_testbed2:22         0a

v6280-top> storage load summary

Port   Total Load                Switch        Array Port  #Blocks  Array LUN Count

  0c          50%      bs32_testbed1:32  50060e8010138c28     1127               22

  0d          49%      bs32_testbed1:33  50060e8010138c22     1091               18

  0a           0%      BS33_testbed2:32  50060e8010138c20        0               22

  0b           0%      BS33_testbed2:35  50060e8010138c2a        0               18

As you could see above, the array target ports ending with 8c:22/2a and 8c:28/20 are the redundant paths. But all the I/O ends up in just one of the paths to the LUN. Appreciate your feedback. Cheers!

[isaacs · Accepted solution]

Hi Gokula,

DataONTAP will prefer the paths the arrays tells it to.  Unless the array is an active/active array, only the paths to one array controller will be active.  If the array is active/active, and the paths are therefore equal, then DataONTAP will split the LUN access across both paths.

When running DataONTAP 8.1 and later in Cluster Mode, you are able to use 4 paths per array LUN group.  This allows you to have 2 path to the active controller in on an active/passive controller.  Or all 4 on an active/active array.

In your case, ensure that your AMS is running in symmetric active/active multipathing mode, and you should then observe a fairly equal # of array LUNs being accessed on both available paths.

Thanks!

Dan Isaacs

isaacs@netapp.com

[GRANGARAJAN1]

Thanks Dan for the response and feedback. You mentioned "ensure that your AMS is running in symmetric active/active multipathing mode". Is there a specific setting in the AMS that needs to be changed to reflect this mode? If yes, could you please give more details? Thank you again!

[isaacs]

Unfortunately, I do not have much experience with the newer AMS models.  You should be able to contact HDS support and get an answer.

Good luck!

[olgac]

Hi Daniel,

What is the biggest speed that one path can work? Does It depend on what?

Thanks.

Olga.

[isaacs]

Hi Olga,

We can run on 8Gbps Fibre Channel.  That's is currently the highest bandwidth initiator we support.

Thanks!