[OpenIndiana-discuss] spurious degraded multipath messages?

[Richard Elling]

answer below...

On Mar 28, 2012, at 11:54 AM, Dan Swartzendruber wrote:

> On 3/28/2012 2:40 PM, Richard Elling wrote:
>> On Mar 28, 2012, at 11:24 AM, Dan Swartzendruber wrote:
>> 
>>> On 3/28/2012 1:38 PM, Richard Elling wrote:
>>>> On Mar 28, 2012, at 9:52 AM, Dan Swartzendruber wrote:
>>>> 
>>>> 
>>>>> So I have an M1015 and it works fine.  I noticed the other day I hotplugged a crucial M4 into the last free port on the HBA, and later noticed in the dmesg output:
>>>>> 
>>>>> Mar 27 17:55:40 nas genunix: [ID 483743 kern.info] /scsi_vhci/disk at g500a07510324
>>>>> d633 (sd9) multipath status: degraded: path 8 mpt_sas9/disk at w500a07510324d633,0
>>>>> is online
>>>>> 
>>>>> I don't actually have any multipathing.  Is this spurious?
>>>>> 
>>>> No
>>>> 
>>>> 
>>> Let me rephrase.  Is it spurious in my case?  Your second comment seems to imply it is?
>> 
>> No, it is not spurious. It is informational.
>> 
>>>>> Is there some something I can tweak to get rid of stuff like this?
>>>>> 
>>>> Here's a bad idea: configure syslog to ignore kernel info messages.
>>>> Better idea: consider yourself informed and be happy ;-)
>>>> -- richard
>>>> 
>>> See above?
>> 
>> I tend to choose the "better idea"
>> 
> Heh.  Bad choice of words on my part then.  I meant spurious as far as indicating an issue in my configuration.  I assume there is no issue, since I do not multipath?

It is not spurious. More likely you are alarmed by the term "degraded" which is often
used in Solaris to designate when redundancy is suboptimal. In the multipathing code
the description is:

* This framework identifies the client device in three distinct states:
*
* OPTIMAL	- Client device has at least one redundant path.
* DEGRADED	- No redundant paths (critical).  Failure in the current active
*		  path would result in data access failures.
* FAILED	- No paths are available to access this device.

http://src.illumos.org/source/xref/illumos-gate/usr/src/uts/common/sys/mdi_impldefs.h#499

Clearly, since the device can be multipathed, but there is only one operational path, the
status is degraded.

Don't worry, be happy.
 -- richard

--
DTrace Conference, April 3, 2012, http://wiki.smartos.org/display/DOC/dtrace.conf
ZFS Performance and Training
Richard.Elling at RichardElling.com
+1-760-896-4422