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CAMCONTROL(8)		  BSD System Manager's Manual		 CAMCONTROL(8)

     camcontrol — CAM control program

     camcontrol ⟨command⟩ [device id] [generic args] [command args]
     camcontrol devlist [-v]
     camcontrol periphlist [device id] [-n dev_name] [-u unit_number]
     camcontrol tur [device id] [generic args]
     camcontrol inquiry [device id] [generic args] [-D] [-S] [-R]
     camcontrol identify [device id] [generic args] [-v]
     camcontrol reportluns [device id] [generic args] [-c] [-l]
		[-r reporttype]
     camcontrol readcap [device id] [generic args] [-b] [-h] [-H] [-N] [-q]
     camcontrol start [device id] [generic args]
     camcontrol stop [device id] [generic args]
     camcontrol load [device id] [generic args]
     camcontrol eject [device id] [generic args]
     camcontrol rescan ⟨all | bus[:target:lun]⟩
     camcontrol reset ⟨all | bus[:target:lun]⟩
     camcontrol defects [device id] [generic args] ⟨-f format⟩ [-P] [-G]
     camcontrol modepage [device id] [generic args] ⟨-m page | -l⟩ [-P pgctl]
		[-b | -e] [-d]
     camcontrol cmd [device id] [generic args] ⟨-a cmd [args]⟩ ⟨-c cmd [args]⟩
		[-d] [-f] [-i len fmt] [-o len fmt [args]] [-r fmt]
     camcontrol debug [-I] [-P] [-T] [-S] [-X] [-c]
     camcontrol tags [device id] [generic args] [-N tags] [-q] [-v]
     camcontrol negotiate [device id] [generic args] [-c] [-D enable|disable]
		[-M mode] [-O offset] [-q] [-R syncrate] [-T enable|disable]
		[-U] [-W bus_width] [-v]
     camcontrol format [device id] [generic args] [-q] [-r] [-w] [-y]
     camcontrol idle [device id] [generic args] [-t time]
     camcontrol standby [device id] [generic args] [-t time]
     camcontrol sleep [device id] [generic args]
     camcontrol help

     The camcontrol utility is designed to provide a way for users to access
     and control the FreeBSD CAM subsystem.

     The camcontrol utility can cause a loss of data and/or system crashes if
     used improperly.  Even expert users are encouraged to exercise caution
     when using this command.  Novice users should stay away from this util‐

     The camcontrol utility has a number of primary functions, many of which
     support an optional device identifier.  A device identifier can take one
     of three forms:

     deviceUNIT	     Specify a device name and unit number combination, like
		     "da5" or "cd3".

     bus:target	     Specify a bus number and target id.  The bus number can
		     be determined from the output of “camcontrol devlist”.
		     The lun defaults to 0.

     bus:target:lun  Specify the bus, target and lun for a device.  (e.g.

     The device identifier, if it is specified, must come immediately after
     the function name, and before any generic or function-specific arguments.
     Note that the -n and -u arguments described below will override any
     device name or unit number specified beforehand.  The -n and -u arguments
     will not override a specified bus:target or bus:target:lun, however.

     Most of the camcontrol primary functions support these generic arguments:

     -C count	     SCSI command retry count.	In order for this to work,
		     error recovery (-E) must be turned on.

     -E		     Instruct the kernel to perform generic SCSI error recov‐
		     ery for the given command.	 This is needed in order for
		     the retry count (-C) to be honored.  Other than retrying
		     commands, the generic error recovery in the code will
		     generally attempt to spin up drives that are not spin‐
		     ning.  It may take some other actions, depending upon the
		     sense code returned from the command.

     -n dev_name     Specify the device type to operate on, e.g. "da", "cd".

     -t timeout	     SCSI command timeout in seconds.  This overrides the
		     default timeout for any given command.

     -u unit_number  Specify the device unit number, e.g. "1", "5".

     -v		     Be verbose, print out sense information for failed SCSI

     Primary command functions:

     devlist	 List all physical devices (logical units) attached to the CAM
		 subsystem.  This also includes a list of peripheral drivers
		 attached to each device.  With the -v argument, SCSI bus num‐
		 ber, adapter name and unit numbers are printed as well.

     periphlist	 List all peripheral drivers attached to a given physical
		 device (logical unit).

     tur	 Send the SCSI test unit ready (0x00) command to the given
		 device.  The camcontrol utility will report whether the
		 device is ready or not.

     inquiry	 Send a SCSI inquiry command (0x12) to a device.  By default,
		 camcontrol will print out the standard inquiry data, device
		 serial number, and transfer rate information.	The user can
		 specify that only certain types of inquiry data be printed:

		 -D    Get the standard inquiry data.

		 -S    Print out the serial number.  If this flag is the only
		       one specified, camcontrol will not print out "Serial
		       Number" before the value returned by the drive.	This
		       is to aid in script writing.

		 -R    Print out transfer rate information.

     identify	 Send a ATA identify command (0xec) to a device.

     reportluns	 Send the SCSI REPORT LUNS (0xA0) command to the given device.
		 By default, camcontrol will print out the list of logical
		 units (LUNs) supported by the target device.  There are a
		 couple of options to modify the output:

		 -c		 Just print out a count of LUNs, not the
				 actual LUN numbers.

		 -l		 Just print out the LUNs, and don't print out
				 the count.

		 -r reporttype	 Specify the type of report to request from
				 the target:

				 default    Return the default report.	This
					    is the camcontrol default.	Most
					    targets will support this report
					    if they support the REPORT LUNS

				 wellknown  Return only well known LUNs.

				 all	    Return all available LUNs.

		 camcontrol will try to print out LUN numbers in a reasonable
		 format.  It can understand the peripheral, flat, LUN and
		 extended LUN formats.

     readcap	 Send the SCSI READ CAPACITY command to the given device and
		 display the results.  If the device is larger than 2TB, the
		 SCSI READ CAPACITY (16) service action will be sent to obtain
		 the full size of the device.  By default, camcontrol will
		 print out the last logical block of the device, and the
		 blocksize of the device in bytes.  To modify the output for‐
		 mat, use the following options:

		 -b	Just print out the blocksize, not the last block or
			device size.  This cannot be used with -N or -s.

		 -h	Print out the device size in human readable (base 2,
			1K == 1024) format.  This implies -N and cannot be
			used with -q or -b.

		 -H	Print out the device size in human readable (base 10,
			1K == 1000) format.

		 -N	Print out the number of blocks in the device instead
			of the last logical block.

		 -q	Quiet, print out the numbers only (separated by a
			comma if -b or -s are not specified).

		 -s	Print out the last logical block or the size of the
			device only, and omit the blocksize.

     start	 Send the SCSI Start/Stop Unit (0x1B) command to the given
		 device with the start bit set.

     stop	 Send the SCSI Start/Stop Unit (0x1B) command to the given
		 device with the start bit cleared.

     load	 Send the SCSI Start/Stop Unit (0x1B) command to the given
		 device with the start bit set and the load/eject bit set.

     eject	 Send the SCSI Start/Stop Unit (0x1B) command to the given
		 device with the start bit cleared and the load/eject bit set.

     rescan	 Tell the kernel to scan all busses in the system (with the
		 all argument), the given bus (XPT_SCAN_BUS), or bus:tar‐
		 get:lun (XPT_SCAN_LUN) for new devices or devices that have
		 gone away.  The user may specify a scan of all busses, a sin‐
		 gle bus, or a lun.  Scanning all luns on a target is not sup‐

     reset	 Tell the kernel to reset all busses in the system (with the
		 all argument) or the given bus (XPT_RESET_BUS) by issuing a
		 SCSI bus reset for that bus, or to reset the given bus:tar‐
		 get:lun (XPT_RESET_DEV), typically by issuing a BUS DEVICE
		 RESET message after connecting to that device.	 Note that
		 this can have a destructive impact on the system.

     defects	 Send the SCSI READ DEFECT DATA (10) command (0x37) to the
		 given device, and print out any combination of: the total
		 number of defects, the primary defect list (PLIST), and the
		 grown defect list (GLIST).

		 -f format    The three format options are: block, to print
			      out the list as logical blocks, bfi, to print
			      out the list in bytes from index format, and
			      phys, to print out the list in physical sector
			      format.  The format argument is required.	 Most
			      drives support the physical sector format.  Some
			      drives support the logical block format.	Many
			      drives, if they do not support the requested
			      format, return the data in an alternate format,
			      along with sense information indicating that the
			      requested data format is not supported.  The
			      camcontrol utility attempts to detect this, and
			      print out whatever format the drive returns.  If
			      the drive uses a non-standard sense code to
			      report that it does not support the requested
			      format, camcontrol will probably see the error
			      as a failure to complete the request.

		 -G	      Print out the grown defect list.	This is a list
			      of bad blocks that have been remapped since the
			      disk left the factory.

		 -P	      Print out the primary defect list.

		 If neither -P nor -G is specified, camcontrol will print out
		 the number of defects given in the READ DEFECT DATA header
		 returned from the drive.

     modepage	 Allows the user to display and optionally edit a SCSI mode
		 page.	The mode page formats are located in
		 /usr/share/misc/scsi_modes.  This can be overridden by speci‐
		 fying a different file in the SCSI_MODES environment vari‐
		 able.	The modepage command takes several arguments:

		 -d	       Disable block descriptors for mode sense.

		 -b	       Displays mode page data in binary format.

		 -e	       This flag allows the user to edit values in the
			       mode page.  The user may either edit mode page
			       values with the text editor pointed to by his
			       EDITOR environment variable, or supply mode
			       page values via standard input, using the same
			       format that camcontrol uses to display mode
			       page values.  The editor will be invoked if
			       camcontrol detects that standard input is ter‐

		 -l	       Lists all available mode pages.

		 -m mode_page  This specifies the number of the mode page the
			       user would like to view and/or edit.  This
			       argument is mandatory unless -l is specified.

		 -P pgctl      This allows the user to specify the page con‐
			       trol field.  Possible values are:
			       0    Current values
			       1    Changeable values
			       2    Default values
			       3    Saved values

     cmd	 Allows the user to send an arbitrary ATA or SCSI CDB to any
		 device.  The cmd function requires the -c argument to specify
		 SCSI CDB or the -a argument to specify ATA Command Block reg‐
		 isters values.	 Other arguments are optional, depending on
		 the command type.  The command and data specification syntax
		 is documented in cam_cdbparse(3).  NOTE: If the CDB specified
		 causes data to be transfered to or from the SCSI device in
		 question, you MUST specify either -i or -o.

		 -a cmd [args]	    This specifies the content of 12 ATA Com‐
				    mand Block registers (command, features,
				    lba_low, lba_mid, lba_high, device,
				    lba_low_exp, lba_mid_exp.  lba_high_exp,
				    features_exp, sector_count, sec‐

		 -c cmd [args]	    This specifies the SCSI CDB.  SCSI CDBs
				    may be 6, 10, 12 or 16 bytes.

		 -d		    Specifies DMA protocol to be used for ATA

		 -f		    Specifies FPDMA (NCQ) protocol to be used
				    for ATA command.

		 -i len fmt	    This specifies the amount of data to read,
				    and how it should be displayed.  If the
				    format is ‘-’, len bytes of data will be
				    read from the device and written to stan‐
				    dard output.

		 -o len fmt [args]  This specifies the amount of data to be
				    written to a device, and the data that is
				    to be written.  If the format is ‘-’, len
				    bytes of data will be read from standard
				    input and written to the device.

		 -r fmt		    This specifies that 11 result ATA Command
				    Block registers should be displayed (sta‐
				    tus, error, lba_low, lba_mid, lba_high,
				    device, lba_low_exp, lba_mid_exp,
				    lba_high_exp, sector_count, sec‐
				    tor_count_exp), and how.  If the format is
				    ‘-’, 11 result registers will be written
				    to standard output in hex.

     debug	 Turn on CAM debugging printfs in the kernel.  This requires
		 options CAMDEBUG in your kernel config file.  WARNING:
		 enabling debugging printfs currently causes an EXTREME number
		 of kernel printfs.  You may have difficulty turning off the
		 debugging printfs once they start, since the kernel will be
		 busy printing messages and unable to service other requests
		 quickly.  The debug function takes a number of arguments:

		 -I		     Enable CAM_DEBUG_INFO printfs.

		 -P		     Enable CAM_DEBUG_PERIPH printfs.

		 -T		     Enable CAM_DEBUG_TRACE printfs.

		 -S		     Enable CAM_DEBUG_SUBTRACE printfs.

		 -X		     Enable CAM_DEBUG_XPT printfs.

		 -c		     Enable CAM_DEBUG_CDB printfs.  This will
				     cause the kernel to print out the SCSI
				     CDBs sent to the specified device(s).

		 all		     Enable debugging for all devices.

		 off		     Turn off debugging for all devices

		 bus[:target[:lun]]  Turn on debugging for the given bus, tar‐
				     get or lun.  If the lun or target and lun
				     are not specified, they are wildcarded.
				     (i.e., just specifying a bus turns on
				     debugging printfs for all devices on that

     tags	 Show or set the number of "tagged openings" or simultaneous
		 transactions we attempt to queue to a particular device.  By
		 default, the tags command, with no command-specific arguments
		 (i.e., only generic arguments) prints out the "soft" maximum
		 number of transactions that can be queued to the device in
		 question.  For more detailed information, use the -v argument
		 described below.

		 -N tags  Set the number of tags for the given device.	This
			  must be between the minimum and maximum number set
			  in the kernel quirk table.  The default for most
			  devices that support tagged queueing is a minimum of
			  2 and a maximum of 255.  The minimum and maximum
			  values for a given device may be determined by using
			  the -v switch.  The meaning of the -v switch for
			  this camcontrol subcommand is described below.

		 -q	  Be quiet, and do not report the number of tags.
			  This is generally used when setting the number of

		 -v	  The verbose flag has special functionality for the
			  tags argument.  It causes camcontrol to print out
			  the tagged queueing related fields of the

			  dev_openings	 This is the amount of capacity for
					 transactions queued to a given

			  dev_active	 This is the number of transactions
					 currently queued to a device.

			  devq_openings	 This is the kernel queue space for
					 transactions.	This count usually
					 mirrors dev_openings except during
					 error recovery operations when the
					 device queue is frozen (device is not
					 allowed to receive commands), the
					 number of dev_openings is reduced, or
					 transaction replay is occurring.

			  devq_queued	 This is the number of transactions
					 waiting in the kernel queue for
					 capacity on the device.  This number
					 is usually zero unless error recovery
					 is in progress.

			  held		 The held count is the number of CCBs
					 held by peripheral drivers that have
					 either just been completed or are
					 about to be released to the transport
					 layer for service by a device.	 Held
					 CCBs reserve capacity on a given

			  mintags	 This is the current "hard" minimum
					 number of transactions that can be
					 queued to a device at once.  The
					 dev_openings value above cannot go
					 below this number.  The default value
					 for mintags is 2, although it may be
					 set higher or lower for various

			  maxtags	 This is the "hard" maximum number of
					 transactions that can be queued to a
					 device at one time.  The dev_openings
					 value cannot go above this number.
					 The default value for maxtags is 255,
					 although it may be set higher or
					 lower for various devices.

     negotiate	 Show or negotiate various communication parameters.  Some
		 controllers may not support setting or changing some of these
		 values.  For instance, the Adaptec 174x controllers do not
		 support changing a device's sync rate or offset.  The
		 camcontrol utility will not attempt to set the parameter if
		 the controller indicates that it does not support setting the
		 parameter.  To find out what the controller supports, use the
		 -v flag.  The meaning of the -v flag for the negotiate com‐
		 mand is described below.  Also, some controller drivers do
		 not support setting negotiation parameters, even if the
		 underlying controller supports negotiation changes.  Some
		 controllers, such as the Advansys wide controllers, support
		 enabling and disabling synchronous negotiation for a device,
		 but do not support setting the synchronous negotiation rate.

		 -a		    Attempt to make the negotiation settings
				    take effect immediately by sending a Test
				    Unit Ready command to the device.

		 -c		    Show or set current negotiation settings.
				    This is the default.

		 -D enable|disable  Enable or disable disconnection.

		 -M mode	    Set ATA mode.

		 -O offset	    Set the command delay offset.

		 -q		    Be quiet, do not print anything.  This is
				    generally useful when you want to set a
				    parameter, but do not want any status

		 -R syncrate	    Change the synchronization rate for a
				    device.  The sync rate is a floating point
				    value specified in MHz.  So, for instance,
				    ‘20.000’ is a legal value, as is ‘20’.

		 -T enable|disable  Enable or disable tagged queueing for a

		 -U		    Show or set user negotiation settings.
				    The default is to show or set current
				    negotiation settings.

		 -v		    The verbose switch has special meaning for
				    the negotiate subcommand.  It causes
				    camcontrol to print out the contents of a
				    Path Inquiry (XPT_PATH_INQ) CCB sent to
				    the controller driver.

		 -W bus_width	    Specify the bus width to negotiate with a
				    device.  The bus width is specified in
				    bits.  The only useful values to specify
				    are 8, 16, and 32 bits.  The controller
				    must support the bus width in question in
				    order for the setting to take effect.

		 In general, sync rate and offset settings will not take
		 effect for a device until a command has been sent to the
		 device.  The -a switch above will automatically send a Test
		 Unit Ready to the device so negotiation parameters will take

     format	 Issue the SCSI FORMAT UNIT command to the named device.


		 Low level formatting a disk will destroy ALL data on the
		 disk.	Use extreme caution when issuing this command.	Many
		 users low-level format disks that do not really need to be
		 low-level formatted.  There are relatively few scenarios that
		 call for low-level formatting a disk.	One reason for low-
		 level formatting a disk is to initialize the disk after
		 changing its physical sector size.  Another reason for low-
		 level formatting a disk is to revive the disk if you are get‐
		 ting "medium format corrupted" errors from the disk in
		 response to read and write requests.

		 Some disks take longer than others to format.	Users should
		 specify a timeout long enough to allow the format to com‐
		 plete.	 The default format timeout is 3 hours, which should
		 be long enough for most disks.	 Some hard disks will complete
		 a format operation in a very short period of time (on the
		 order of 5 minutes or less).  This is often because the drive
		 does not really support the FORMAT UNIT command -- it just
		 accepts the command, waits a few minutes and then returns it.

		 The ‘format’ subcommand takes several arguments that modify
		 its default behavior.	The -q and -y arguments can be useful
		 for scripts.

		 -q	 Be quiet, do not print any status messages.  This
			 option will not disable the questions, however.  To
			 disable questions, use the -y argument, below.

		 -r	 Run in “report only” mode.  This will report status
			 on a format that is already running on the drive.

		 -w	 Issue a non-immediate format command.	By default,
			 camcontrol issues the FORMAT UNIT command with the
			 immediate bit set.  This tells the device to immedi‐
			 ately return the format command, before the format
			 has actually completed.  Then, camcontrol gathers
			 SCSI sense information from the device every second
			 to determine how far along in the format process it
			 is.  If the -w argument is specified, camcontrol will
			 issue a non-immediate format command, and will be
			 unable to print any information to let the user know
			 what percentage of the disk has been formatted.

		 -y	 Do not ask any questions.  By default, camcontrol
			 will ask the user if he/she really wants to format
			 the disk in question, and also if the default format
			 command timeout is acceptable.	 The user will not be
			 asked about the timeout if a timeout is specified on
			 the command line.

     idle	 Put ATA device into IDLE state. Optional parameter (-t) spec‐
		 ifies automatic standby timer value in seconds. Value 0 dis‐
		 ables timer.

     standby	 Put ATA device into STANDBY state. Optional parameter (-t)
		 specifies automatic standby timer value in seconds. Value 0
		 disables timer.

     sleep	 Put ATA device into SLEEP state. Note that the only way get
		 device out of this state may be reset.

     help	 Print out verbose usage information.

     The SCSI_MODES variable allows the user to specify an alternate mode page
     format file.

     The EDITOR variable determines which text editor camcontrol starts when
     editing mode pages.

     /usr/share/misc/scsi_modes	 is the SCSI mode format database.
     /dev/xpt0			 is the transport layer device.
     /dev/pass*			 are the CAM application passthrough devices.

	   camcontrol eject -n cd -u 1 -v

     Eject the CD from cd1, and print SCSI sense information if the command

	   camcontrol tur da0

     Send the SCSI test unit ready command to da0.  The camcontrol utility
     will report whether the disk is ready, but will not display sense infor‐
     mation if the command fails since the -v switch was not specified.

	   camcontrol tur da1 -E -C 4 -t 50 -v

     Send a test unit ready command to da1.  Enable kernel error recovery.
     Specify a retry count of 4, and a timeout of 50 seconds.  Enable sense
     printing (with the -v flag) if the command fails.	Since error recovery
     is turned on, the disk will be spun up if it is not currently spinning.
     The camcontrol utility will report whether the disk is ready.

	   camcontrol cmd -n cd -u 1 -v -c "3C 00 00 00 00 00 00 00 0e 00" \
		   -i 0xe "s1 i3 i1 i1 i1 i1 i1 i1 i1 i1 i1 i1"

     Issue a READ BUFFER command (0x3C) to cd1.	 Display the buffer size of
     cd1, and display the first 10 bytes from the cache on cd1.	 Display SCSI
     sense information if the command fails.

	   camcontrol cmd -n cd -u 1 -v -c "3B 00 00 00 00 00 00 00 0e 00" \
		   -o 14 "00 00 00 00 1 2 3 4 5 6 v v v v" 7 8 9 8

     Issue a WRITE BUFFER (0x3B) command to cd1.  Write out 10 bytes of data,
     not including the (reserved) 4 byte header.  Print out sense information
     if the command fails.  Be very careful with this command, improper use
     may cause data corruption.

	   camcontrol modepage da3 -m 1 -e -P 3

     Edit mode page 1 (the Read-Write Error Recover page) for da3, and save
     the settings on the drive.	 Mode page 1 contains a disk drive's auto read
     and write reallocation settings, among other things.

	   camcontrol rescan all

     Rescan all SCSI busses in the system for devices that have been added,
     removed or changed.

	   camcontrol rescan 0

     Rescan SCSI bus 0 for devices that have been added, removed or changed.

	   camcontrol rescan 0:1:0

     Rescan SCSI bus 0, target 1, lun 0 to see if it has been added, removed,
     or changed.

	   camcontrol tags da5 -N 24

     Set the number of concurrent transactions for da5 to 24.

	   camcontrol negotiate -n da -u 4 -T disable

     Disable tagged queueing for da4.

	   camcontrol negotiate -n da -u 3 -R 20.000 -O 15 -a

     Negotiate a sync rate of 20MHz and an offset of 15 with da3.  Then send a
     Test Unit Ready command to make the settings take effect.

     cam(3), cam_cdbparse(3), cam(4), pass(4), xpt(4)

     The camcontrol utility first appeared in FreeBSD 3.0.

     The mode page editing code and arbitrary SCSI command code are based upon
     code in the old scsi(8) utility and scsi(3) library, written by Julian
     Elischer and Peter Dufault.  The scsi(8) program first appeared in 386BSD, and first appeared in FreeBSD in FreeBSD 2.0.5.

     Kenneth Merry ⟨⟩

     The code that parses the generic command line arguments does not know
     that some of the subcommands take multiple arguments.  So if, for
     instance, you tried something like this:

	   camcontrol cmd -n da -u 1 -c "00 00 00 00 00 v" 0x00 -v

     The sense information from the test unit ready command would not get
     printed out, since the first getopt(3) call in camcontrol bails out when
     it sees the second argument to -c (0x00), above.  Fixing this behavior
     would take some gross code, or changes to the getopt(3) interface.	 The
     best way to circumvent this problem is to always make sure to specify
     generic camcontrol arguments before any command-specific arguments.

BSD				 July 1, 2010				   BSD

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