Why I did it
Some products might experience an occasional IO failure in the communication between CPU and SSD.
Based on some research it could be attributable to some device not handling ATA NCQ (Native Command Queue).
This issue currently affect 4 products:
DCS-7170-32C*
DCS-7170-64C
DCS-7060DX4-32
DCS-7260CX3-64
How I did it
This change disable NCQ on the affected drive for a small set of products.
How to verify it
When the fix is applied, these 2 patterns can be found in the dmesg.
ata1.00: FORCE: horkage modified (noncq)
NCQ (not used)
Test results using: fio --direct=1 --rw=randrw --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4
with NCQ (ata1.00: 61865984 sectors, multi 1: LBA48 NCQ (depth 32), AA)
READ: bw=33.9MiB/s (35.6MB/s), 33.9MiB/s-33.9MiB/s (35.6MB/s-35.6MB/s), io=4073MiB (4270MB), run=120078-120078msec
WRITE: bw=34.1MiB/s (35.8MB/s), 34.1MiB/s-34.1MiB/s (35.8MB/s-35.8MB/s), io=4100MiB (4300MB), run=120078-120078msec
without NCQ (ata1.00: 61865984 sectors, multi 1: LBA48 NCQ (not used))
READ: bw=31.7MiB/s (33.3MB/s), 31.7MiB/s-31.7MiB/s (33.3MB/s-33.3MB/s), io=3808MiB (3993MB), run=120083-120083msec
WRITE: bw=31.9MiB/s (33.4MB/s), 31.9MiB/s-31.9MiB/s (33.4MB/s-33.4MB/s), io=3830MiB (4016MB), run=120083-120083msec
Which release branch to backport (provide reason below if selected)
638fdd0e93