IJ46272: PERFORMANCE DEGRADED AFTER ENABLE QOS ON SYSTEM POOL

APAR status

• Closed as program error.

Error description

• After configuring qos on two ess io node, overall
  performance dropped significantly:
  
  mmchqos gpfs0 --enable -N gssXXX-1-hs,gssXXX-2-hs
         pool=system,maintenance=20000IOPS,other=unlimited
  
  QOS configuration has been installed and broadcast to all
  nodes.
  
  Issue was reported on GPFS 5.1.4.1
  

Local fix

• waiting for dev xapar update
  

Problem summary

• With QoS throttling configuration on a subset of nodes in the
  cluster, the I/Os on the rest client nodes without QoS
  throttling are seriously throttled unexpectedly.
  

Problem conclusion

• This problem is fixed in 5.1.2.11
  To see all Spectrum Scale APARs and their respective
  Fix solutions refer to page:
  https://public.dhe.ibm.com/storage/spectrumscale/spectrum_scale_
  apars.html
  
  Benefits of the solution:
  Address the unexpected I/O hang on the non-QoS throttled client
  nodes after configuring QoS for some client nodes.
  
  Work Around:
  Create a node class for the non-QoS throttled nodes and set
  "unlimited" QoS throttling for that node class when configuring
  QoS for a subset nodes in the cluster.
  
  Problem trigger:
  Configure QoS throttling for a subset nodes in the cluster.
  
  Symptom:
  I/O hang
  
  Platforms affected:
  All Operating Systems
  
  Functional Area affected:
  QoS
  
  Customer Impact:
  High Importance
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IJ45446

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  SPEC SCALE DME

• Fixed component ID

  5737F34AP

Applicable component levels