svn commit: r186903 - head/share/man/man4
imp at FreeBSD.org
Thu Jan 8 07:20:33 PST 2009
Date: Thu Jan 8 15:20:32 2009
New Revision: 186903
First cut at documenting hw.cam.cd.retry_count. Moved
kern.cam.cd.%d.minimum_cmd_size to new SYSCTL VARIABLES section.
--- head/share/man/man4/cd.4 Thu Jan 8 13:32:08 2009 (r186902)
+++ head/share/man/man4/cd.4 Thu Jan 8 15:20:32 2009 (r186903)
@@ -25,7 +25,7 @@
-.Dd September 2, 2003
+.Dd January 8, 2009
.Dt CD 4
@@ -370,43 +370,6 @@ Some work is planned to support
some of the more common `broken'
drives; however, this is not yet under way.
-driver attempts to automatically determine whether the drive it is talking
-to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations.
-drives only support 6 byte commands, and
-drives only support 10 byte commands.
-driver first attempts to determine whether the protocol in use typically
-supports 6 byte commands by issuing a CAM Path Inquiry CCB.
-It will then default to 6 byte or 10 byte commands as appropriate.
-After that, the
-driver defaults to using 6 byte commands (assuming the protocol the drive
-speaks claims to support 6 byte commands), until one fails with a
-ILLEGAL REQUEST error.
-Then it tries the 10 byte version of the command to
-see if that works instead.
-Users can change the default via per-drive
-sysctl variables and loader tunables.
-The variable names are the same in
-is the unit number of the drive in question.
-Valid minimum command sizes
-are 6 and 10.
-Any value above 6 will be rounded to 10, and any value below
-6 will be rounded to 6.
.Sh CHANGER OPERATION
This driver has built-in support for LUN-based CD changers.
A LUN-based CD
@@ -466,6 +429,63 @@ probe messages for the various LUNs of t
while the boot process is going on.
This is normal, and is caused by the
changer scheduling code.
+.Sh SYSCTL VARIABLES
+The following variables are available as both
+.Xr sysctl 8
+.Xr loader 8
+.Bl -tag -width 12
+This variable determines how many times the
+driver will retry a READ or WRITE command.
+This does not affect the number of retries used during probe time or for
+driver dump routine.
+This value currently defaults to 4.
+driver attempts to automatically determine whether the drive it is talking
+to supports 6 byte or 10 byte MODE SENSE/MODE SELECT operations.
+drives only support 6 byte commands, and
+drives only support 10 byte commands.
+driver first attempts to determine whether the protocol in use typically
+supports 6 byte commands by issuing a CAM Path Inquiry CCB.
+It will then default to 6 byte or 10 byte commands as appropriate.
+After that, the
+driver defaults to using 6 byte commands (assuming the protocol the drive
+speaks claims to support 6 byte commands), until one fails with a
+ILLEGAL REQUEST error.
+Then it tries the 10 byte version of the command to
+see if that works instead.
+Users can change the default via per-drive
+sysctl variables and loader tunables.
+is the unit number of the drive in question.
+Valid minimum command sizes
+are 6 and 10.
+Any value above 6 will be rounded to 10, and any value below
+6 will be rounded to 6.
+Tune how long individual LUNs are 'locked' for I/O operations to
+optimize changer operation.
+See CHANGER OPERATION section for information on how to use these items.
.Bl -tag -width /dev/cd[0-9][a-h] -compact
.It Pa /dev/cd[0-9][a-h]
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