- Why I did it
Based on some research some products might experience an occasional IO failures in the communication between CPU and SSD because of NCQ.
There seems to be a problem between some kernel versions and some SATA controllers.
Syslog error message examples:
Error "ata1: SError: { UnrecovData Handshk }" - "failed command: WRITE FPDMA QUEUED".
Error "ata1: SError: { RecovComm HostInt PHYRdyChg CommWake 10B8B DevExch }" - "failed command: READ FPDMA QUEUED".
Some vendors already disabled NCQ on their platforms in SONiC due to similar issue:
[Arista] Disable ATA NCQ for a few products #13739 [Arista] Disable ATA NCQ for a few products
[Arista] Disable SSD NCQ on DCS-7050CX3-32S #13964 [Arista] Disable SSD NCQ on DCS-7050CX3-32S
Also there are other discussions on Debian/Ubuntu forums about similar issues and it was suggested to disable NCQ:
https://askubuntu.com/questions/133946/are-these-sata-errors-dangerous
- How I did it
Add a kernel parameter to tell libata to disable NCQ
- How to verify it
Use FIO tool - fio --direct=1 --rw=randrw --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4
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