FS System: Non Optimized Access Events Observed When Veritas DMP Used for Multipathing

Asset ID:	1-72-2129001.1
Update Date:	2016-12-01
Keywords:

Solution Type Problem Resolution Sure

Solution 2129001.1 : FS System: Non Optimized Access Events Observed When Veritas DMP Used for Multipathing

Applies to:

Oracle FS1-2 Flash Storage System - Version 6.1 and later
Information in this document applies to any platform.

Symptoms

SAN_EVENT_SLUN_NON_OPTIMIZED_ACCESS events are observed in the Oracle Flash Storage FS1-2 event logs when the Oracle Flash Storage FS1-2 is accessed by hosts with Veritas DMP to manage multipathing.

Cause

Oracle Flash Storage FS1-2 should be recognized as ALUA (with Veritas naming conventions Asynchronous Active/Active (A/A-A)) array by Veritas DMP in order to manage multipathing correctly.

Solution

There may be times when an end user notes a lot of "Non-Optimized Access" (NOA) entries in the event log of FS1.

Each LUN on the FS1 System has an owning Controller that handles cache and access data for that LUN. Optimized access is taken through the Fibre Channel ports on that Controller.

A Non-Optimized Access is generated when a host accesses a LUN from a port that is not on the owning Controller. The request needs to be forwarded to the owning Controller, which takes CPU and back-end overhead from both Controllers and causes an overall lag on the Oracle Flash Storage FS1-2.

Oracle Flash Storage FS1-2 should be recognized as ALUA [with Veritas naming conventions Asynchronous Active/Active (A/A-A)] array by Veritas DMP in order to manage multipathing correctly.

Please follow below verification actions when NOA events are seen on Oracle Flash Storage FS1-2 logs:

Check that the environment is compatible as per the Interoperability Guide. Oracle Flash Storage System Support and Interoperability Guide is available from the link below:

http://docs.oracle.com/en/storage/#fla
“Disable Reference Tag Checking” for each Oracle Flash Storage FS1-2 LUN provisioned to VERITAS hosts if not already done. Check document below for details:
<Document 1955116.1> FS System: When To Use "Use as Boot LUN" and "Disable Reference Tag Checking" Options For FS1-2 LUNs
Check that the Veritas Array Support Library (ASL) is installed and active:

# vxddladm listsupport libname=libvxoracle-FS1.so

ATTR_NAME ATTR_VALUE
=================================================================================================
LIBNAME libvxoracle-FS1.so
VID Oracle
PID Oracle FS1-2
ARRAY_TYPE ALUA
ARRAY_NAME Oracle-FS1-2-

The library name may be different. Please check the following page on the Veritas website to get the correct package, version and library name:
https://sort.veritas.com/asl/matrix
Check Veritas status:
1. If the Oracle Flash Storage FS1-2 is detected as an ALUA array:
  
  # vxdmpadm listenclosure
  
  ENCLR_NAME ENCLR_TYPE ENCLR_SNO STATUS ARRAY_TYPE LUN_COUNT FIRMWARE
  ===================================================================================================
  ...
  oracle-fs1-2-0 Oracle-FS1-2- 414B3030333235333931 CONNECTED ALUA 102 6201
  ...
2. Check Veritas can see both controllers correctly:
  
  # vxdmpadm listctlr all
  
  CTLR_NAME ENCLR_TYPE STATE ENCLR_NAME PATH_COUNT
  =========================================================================
  c6 Disk ENABLED disk 1
  c3 Oracle-FS1-2- ENABLED oracle-fs1-2-0 306
  c5 Oracle-FS1-2- ENABLED oracle-fs1-2-0 306
3. Check that Veritas can correctly recognize the paths as PRIMARY and SECONDARY:
  
  # vxdmpadm getsubpaths ctlr=c3
  
  NAME STATE[A] PATH-TYPE[M] DMPNODENAME ENCLR-TYPE ENCLR-NAME ATTRS
  ================================================================================
  sda ENABLED PRIMARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdcz ENABLED(A) SECONDARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdgx ENABLED PRIMARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdb ENABLED(A) SECONDARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdda ENABLED PRIMARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdgy ENABLED(A) SECONDARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdc ENABLED PRIMARY oracle-fs1-2-0_00002 Oracle-FS1-2- oracle-fs1-2-0 -
  sddb ENABLED(A) SECONDARY oracle-fs1-2-0_00002 Oracle-FS1-2- oracle-fs1-2-0 -
  # vxdmpadm getsubpaths ctlr=c5
  
  NAME STATE[A] PATH-TYPE[M] DMPNODENAME ENCLR-TYPE ENCLR-NAME ATTRS
  ================================================================================
  sdkv ENABLED PRIMARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdot ENABLED(A) SECONDARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdsr ENABLED(A) SECONDARY oracle-fs1-2-0_00000 Oracle-FS1-2- oracle-fs1-2-0 -
  sdkw ENABLED(A) SECONDARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdou ENABLED PRIMARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdss ENABLED PRIMARY oracle-fs1-2-0_00001 Oracle-FS1-2- oracle-fs1-2-0 -
  sdkx ENABLED PRIMARY oracle-fs1-2-0_00002 Oracle-FS1-2- oracle-fs1-2-0 -
  sdov ENABLED(A) SECONDARY oracle-fs1-2-0_00002 Oracle-FS1-2- oracle-fs1-2-0 -
Check DMP I/O policy used by Veritas configuration.
The qualification for Veritas DMP is done with singleactive and round-robin policy. Correct DMP I/O policy if it is different than singleactive or round-robin.

# vxdmpadm getattr enclosure oracle-fs1-2-0 iopolicy

ENCLR_NAME DEFAULT CURRENT
===========================================
oracle-fs1 MinimumQ MinimumQ

Please refer to Veritas documentation about changing the DMP I/O policy:
https://www.veritas.com/support/en_US/article.000056446
Round-robin works fine but there are cases where NOAs can be observed while DMP I/O policy is set to round-robin. NOA events can be stopped by setting the DMP I/O policy to singleactive. Request Veritas Support to investigate and fix the issue.

Below scenarios were observed during qualification tests:

Changing DMP I/O policy to singleactive eliminates NOA errors on the Oracle Flash Storage FS1-2.
Reducing the number of IO paths to less than 6 paths eliminates NOA errors on the Oracle Flash Storage FS1-2 while DMP I/O policy is set to round-robin.

References

<NOTE:1955116.1> - FS System: When To Use "Use as Boot LUN" and "Disable Reference Tag Checking" Options For FS1-2 LUNs

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