Skip to main content
NetApp Knowledge Base

How to troubleshoot degraded connectivity from a host to a filer

Last Updated:

Applies to

SAN Protocol


Multipathing (MPIO) software allows the hosts to maintain multiple paths to a LUN. Paths to the NetApp node where a LUN resides are considered "Active/Optimized" while paths through the node's HA partner are considered "Active/Un-Optimized". The exact terminology may vary depending on the host operating system and multipath drivers. Certain scenarios can lead to one or more paths being inaccessible or otherwise unavailable for I/O. Depending on which paths are unavailable, the host may experience performance degradation, especially if there are no other "Active/Optimized" paths remaining. 

Path states are determined by the node that currently owns a LUN using ALUA. When a takeover occurs, the paths through the node that assumes ownership of it's partner's LUNs will become "Active/Optimized".

Example of a path failure in RedHat 'multipath -ll' output: 

# multipath -ll
mpath0 (360a9800043346441464a44424c746e54)
[size=10 GB][features="1 queue_if_no_path"][hwhandler="0"]
_ round-robin 0 [prio=8][active]
_ 0:0:0:0 sda 8:0   [failed][faulty]
_ 1:0:0:0 sdi 8:128 [active][ready]
_ round-robin 0 [prio=2][enabled]
_ 0:0:1:0 sde 8:64  [active][ready]
_ 1:0:1:0 sdm 8:192 [active][ready]

RedHat '/var/log/messages' Examples:

Jun 22 15:55:54 rhel1 multipathd: Lun1: sdcr - tur checker reports path is down
Jun 22 15:55:54 rhel1 multipathd: checker failed path 69:240 in map Lun1
Jun 22 15:55:54 rhel1 multipathd: Lun1: remaining active paths: 3
Jun 22 15:55:54 rhel1 kernel: device-mapper: multipath: Failing path 69:240.

VMware 'vmkernel' Examples:

2017-11-30T07:17:41.351Z cpu15:33143)WARNING: NMP: nmp_DeviceRequestFastDeviceProbe: NMP device "sym.029025256531353837" state in doubt; requested fast path state update...
2017-11-30T07:17:41.351Z cpu15:33143)WARNING: ScsiPath: 4507: Path vmhba2:C0:T0:L55 is being removed
2017-11-30T07:17:41.351Z cpu15:33143)WARNING: ScsiPath: 6117: Remove path: vmhba2:C0:T0:L55

Windows 'System Event Log' Examples:

Information    10/31/2017 4:39:33 PM    mpio        46       None    Path 1000001 was removed from \Device\MPIODisk2 due to a PnP event. The dump data contains the current number of paths.
Information    10/31/2017 4:39:33 PM    ontapdsm    61070    None    Path ID 01000001 was removed.
Warning        10/31/2017 4:39:33 PM    ontapdsm    61054    None    Path ID 01000001 has failed and 02000101 will be used instead.
Error          10/31/2017 4:39:33 PM    ontapdsm    61142    None    Path ID 01000001 has failed.

Note: The exact log entries may vary depending on the operating system version and how multipathing is configured. 


Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.