[gpfsug-discuss] High I/O wait times

[Yaron Daniel]

Hi

Clean all counters on the FC switches and see which port have errors .

For brocade run :

slotstatsclear
statsclear
porterrshow

For cisco run:
 
clear countersall

There might be bad gbic/cable/Storage gbic, which can affect the 
performance, if there is something like that - u can see which ports have 
errors grow over time.
Regards
 


 
 
Yaron Daniel
 94 Em Ha'Moshavot Rd

Storage Architect ? IL Lab Services (Storage)
 Petach Tiqva, 49527
IBM Global Markets, Systems HW Sales
 Israel
 
 
 
Phone:
+972-3-916-5672
 
 
Fax:
+972-3-916-5672
 
 
Mobile:
+972-52-8395593
 
 
e-mail:
yard at il.ibm.com
 
 
IBM Israel
 
 
 
 

       



From:   Jonathan Buzzard <jonathan.buzzard at strath.ac.uk>
To:     gpfsug-discuss at spectrumscale.org
Date:   07/07/2018 11:43 AM
Subject:        Re: [gpfsug-discuss] High I/O wait times
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



On 07/07/18 01:28, Buterbaugh, Kevin L wrote:

[SNIP]

> 
> So, to try to rule out everything but the storage array we replaced the 
> FC cables going from the SAN switches to the array, plugging the new 
> cables into different ports on the SAN switches.  Then we repeated the 
> dd tests from a different NSD server, which both eliminated the NSD 
> server and its? FC cables as a potential cause ? and saw results 
> virtually identical to the previous test.  Therefore, we feel pretty 
> confident that it is the storage array and have let the vendor know all 
> of this.

I was not thinking of doing anything quite as drastic as replacing 
stuff, more look into the logs on the switches in the FC network and 
examine them for packet errors. The above testing didn't eliminate bad 
optics in the storage array itself for example, though it does appear to 
be the storage arrays themselves. Sounds like they could do with a power 
cycle...

JAB.

-- 
Jonathan A. Buzzard                         Tel: +44141-5483420
HPC System Administrator, ARCHIE-WeSt.
University of Strathclyde, John Anderson Building, Glasgow. G4 0NG
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