Module Name: src
Committed By: jdolecek
Date: Mon Jan 13 21:43:06 UTC 2020
Modified Files:
src/share/man/man4: wd.4
Log Message:
document the wd(4) sysctl nodes, and add the note about the Sumsung EVO drives
part of fix for PR kern/54790 and PR kern/54855
To generate a diff of this commit:
cvs rdiff -u -r1.20 -r1.21 src/share/man/man4/wd.4
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man4/wd.4
diff -u src/share/man/man4/wd.4:1.20 src/share/man/man4/wd.4:1.21
--- src/share/man/man4/wd.4:1.20 Wed Jan 9 23:43:13 2019
+++ src/share/man/man4/wd.4 Mon Jan 13 21:43:06 2020
@@ -1,4 +1,4 @@
-.\" $NetBSD: wd.4,v 1.20 2019/01/09 23:43:13 gutteridge Exp $
+.\" $NetBSD: wd.4,v 1.21 2020/01/13 21:43:06 jdolecek Exp $
.\"
.\"
.\" Copyright (c) 1994 James A. Jegers
@@ -64,8 +64,40 @@ and
.Xr badsect 8 ,
the software list supports neither sector replacement nor retention
across reboots.
+.Pp
+The following
+.Xr sysctl 8
+variables control behavior of disks attached using this driver:
+.Bl -tag -width 8n
+.It Dv hw.wdX.use_ncq
+Whether to use NCQ ATA commands for the disk. Only effective when the disk
+hardware actually claims to support NCQ. Default to true.
+.It Dv hw.wdX.use_ncq_prio
+Use optional NCQ priority for high-priority I/O like meta-data. Intended
+only for experimental use right now, might negatively affect performance.
+This setting only has effect if
+.Dv hw.wdX.use_ncq
+is also true.
+Default to false.
+.El
.Sh NOTES
Certain
+.Tn Samsung
+.Tn 860 EVO
+SSD drives have firmware bug which causes interface CRC errors when NCQ
+ATA commands are used. For this reason NCQ is disabled for these drives
+by default.
+Affected drives include, but are not limited to:
+.Pp
+.Bl -tag -width Ds -offset indent -compact
+.It Samsung SSD 860 EVO 500GB
+.It Samsung SSD 860 EVO 1TB
+.El
+.Pp
+It is recommended to not use the EVO SSD drives, and replace them
+with other models.
+.Pp
+Certain
.Tn Seagate
.Tn Barracuda
drives sold around 2003 have a known firmware bug leading to corrupted
