Error: NON_PREFERRED_PATH on Security Analytics storage

Products

• Security Analytics

Issue/Introduction

Security Analytics with external storage (such as Netapp or Dell) have redundant controllers.  There is Controller A and Controller B.  The volumes on the storage array balance themselves between the two controllers to maximize disk I/O.  Of the 6 logical volumes on each storage array, 3 of them will prefer controller A and the other 3 will prefer controller B.  If one of the controllers has an error, the array will push all paths to the other controller for stability reasons.  This is when you may see the NON PREFERRED PATH error message.

You may see this error shortly after a hard drive or a controller was replaced:  Failure Entry 1: NON_PREFERRED_PATH-Recovery Failure Type Code: 10 Storage array: array_name Preferred owner: Controller in slot B Current owner: Controller in slot A.

 

Cause

The volumes need to be redistributed across the controllers evenly.  The controllers have a very sensitive threshold for controller balancing.  If the controllers sense any problem, they will immediately move all volumes to the known good controller.  Sometimes the redistribution back to both controllers doesn't happen automatically and needs to be done manually.

Resolution

If one of the controllers is showing Offline and it was not manually placed Offline, contact technical support for further assistance.

If both controllers are still Online, you can redistribute the volumes using either SANtricity or using the SMcli command from the command line

SANtricity

1. On the affected array, select Storage in the menu
2. Select Volume
3. Select Advanced
4. Click Redistribute Volumes

Command Line

Run this command to display the current volume distribution:

SMcli -n array_name -c 'show allvolumes;' | grep Controller

The correct output should look like this.  Color has been added for emphasis.  Each color grouping maps to one volume.

Preferred owner:               Controller in slot A                             
Current owner:                 Controller in slot A                             
Preferred owner:               Controller in slot B                             
Current owner:                 Controller in slot B                             
Preferred owner:               Controller in slot A                             
Current owner:                 Controller in slot A                             
Preferred owner:               Controller in slot B                             
Current owner:                 Controller in slot B                             
Preferred owner:               Controller in slot A                             
Current owner:                 Controller in slot A                             
Preferred owner:               Controller in slot B                             
Current owner:                 Controller in slot B 

If the preferred paths are incorrect, you will see a mix of A/B instead of AA and BB.

To automatically redistribute the volumes on their preferred paths, run this command:

SMcli -n array_name -c 'reset storageArray volumeDistribution;'

Check the volumes again and confirm that they are all connected to their preferred controller.  If after about 15 minutes, the non-preferred path error message comes back, there may be problems with the controller.  Contact support for further guidance.