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High sequential READ workload latency when using only onboard SAS ports

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Category:
ontap-9
Specialty:
perf
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Applies to

  • AFF80x0
  • ONTAP 9
  • IOM6
  • SAS Adapters PMC-Sierra PM8001 and PM8072

Issue

  • High latency observed from SSDs during peak sequential READ workload.
  • EMS may report errors like below:

[?] Thu Aug 13 20:55:55 EDT [AFF80x0: pmcsas_timeout_1: sas.device.quiesce:debug]: Adapter 0c encountered a command timeout on enclosure services device 0d.01.99. Quiescing the device[?] Thu Aug 13 20:55:58 EDT [AFF80x0: pmcsas_timeout_1: sas.device.timeout:error]: Adapter 0c encountered a device timeout on Enclosure services device 0d.01.99.
[?] Thu Aug 13 20:55:58 EDT [AFF80x0: pmcsas_timeout_1: sas.adapter.debug:info]: params: {'debug_string': 'Level 0 timeout on virtual device: Hard resetting PHY: 0d.01.99 (0xfffff820aaab0040,0x1c,0/0)', 'adapterName': '0c'}
[?] Thu Aug 13 20:55:58 EDT [AFF80x0: scsi_cmdblk_strthr_admin: scsi.cmd.abortedByHost:error]: Enclosure services device 0d.01.99: Command aborted by host adapter: HA status 0x4: cdb 0x1c.

 

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