Update the sa(4) man page for CAM. This was repository-copied from the
st(4) man page. Take out most of the sd(4) and st(4) man pages and point to the new da(4) and sa(4) man pages. Add sa.4 to the makefile. Reviewed by: ken Submitted by: gibbs
This commit is contained in:
Kenneth D. Merry
parent
aa855a598d
commit
190831dd81
@ -3,7 +3,7 @@
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MAN4= bpf.4 ccd.4 cd.4 ch.4 da.4 ddb.4 divert.4 drum.4 fd.4 fpa.4 \
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icmp.4 ifmib.4 inet.4 intro.4 ip.4 ipfirewall.4 \
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lkm.4 lo.4 natm.4 netintro.4 \
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null.4 od.4 pass.4 ppi.4 ppp.4 pt.4 pty.4 route.4 \
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null.4 od.4 pass.4 ppi.4 ppp.4 pt.4 pty.4 route.4 sa.4 \
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scsi.4 sd.4 sl.4 smp.4 snp.4 sppp.4 ssc.4 st.4 su.4 tcp.4 \
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ttcp.4 termios.4 tty.4 tun.4 udp.4 uk.4 update.4 unix.4 vinum.4 vn.4 \
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worm.4 wst.4 xpt.4 yp.4 zero.4
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@ -23,79 +23,35 @@
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id$
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.\" $Id: st.4,v 1.11 1997/03/07 02:49:34 jmg Exp $
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.\"
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.Dd January 17, 1996
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.Dt ST 4
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.Dd October 15, 1998
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.Dt SA 4
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.Os FreeBSD
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.Sh NAME
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.Nm st
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.Nd SCSI tape driver
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.Nm sa
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.Nd SCSI Sequential Access Device Driver
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.Sh SYNOPSIS
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.Cd tape st
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.Cd device st1 at scbus0 target 4 lun 0
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.Cd device sa0
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.Cd device sa1 at scbus0 target 4 lun 0
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for a
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.Nm sa
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driver provides support for all
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.Tn SCSI
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tape. It allows the tape
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to be run in up to four different modes depending on minor numbers
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and supports several different `sub-modes'.
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The device can have both a
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.Em raw
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interface
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and a
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.Em block
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interface; however, only the raw interface is usually used (or recommended).
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In general the interfaces are similar to those described by
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.Xr wt 4
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or
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.Xr mt 4 .
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devices of the sequential access class that are attached to the system
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through a supported
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.Tn SCSI
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Host Adapter.
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The sequential access class includes tape and other linear access devices.
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.Pp
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Where the
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.Xr wt 4
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device has a fairly low level interface to the system,
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.Tn SCSI
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devices have a much higher level interface and talk to the system via
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a
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.Tn SCSI
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adapter and a
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.Tn SCSI
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adapter driver
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(e.g.,
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.Xr ahc 4 ) .
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A
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.Tn SCSI
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Host
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adapter must also be separately configured into the system
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before a
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.Tn SCSI
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tape can be configured.
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.Pp
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As the
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.Tn SCSI
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adapter is probed during boot, the
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.Tn SCSI
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bus is scanned for devices. Any devices found which answer as
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.Sq Em Sequential
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type devices will be attached to the
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.Nm
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driver.
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In
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.Tn FreeBSD
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releases prior to 2.1, the first found is attached as
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.Em st0
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and the next,
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.Em st1 ,
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etc.
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Beginning in
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.Fx 2.1
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it is possible to specify what
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.Nm
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unit a device should
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come on line as; refer to
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.Xr scsi 4
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for details on kernel configuration.
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sequential access device can be configured.
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.Sh MOUNT SESSIONS
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The
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.Nm
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@ -108,59 +64,18 @@ until replaced. The tape can be unmounted, bringing the session to a
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close in several ways. These include:
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.Bl -enum
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.It
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Closing an `unmount device',
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Closing a `rewind device',
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referred to as sub-mode 00 below. An example is
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.Pa /dev/rst0 .
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.Pa /dev/rsa0 .
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.It
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Using the MTOFFL
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.Xr ioctl 2
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command, reachable through the
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.Sq Cm offline
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command of
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.Xr st 1 .
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.It
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Opening a different mode will implicitly unmount the tape, thereby closing
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off the mode that was previously mounted. All parameters will be loaded
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freshly from the new mode. (See below for more on modes.)
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.El
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.Pp
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Parameters that are required to last across the unmounting of a tape
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should be set on the control device. This is sub-mode 3 (see below) and is
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reached through a file with a name of the form
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.Sm off
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.No Xo
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.Pa /dev/st
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.Ar Y
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.Pa ctl.
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.Ar X
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.Xc ,
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.Sm on
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where
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.Ar Y
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is the drive number and
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.Ar X
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is the mode number.
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.Sh MODES AND SUB-MODES
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There are four
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.Sq operation
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modes. These are controlled by bits 2 and 3 of the minor number and
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are designed to allow users to easily read and write different formats
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of tape on devices that allow multiple formats. The parameters for
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each mode can be set individually by hand with the
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.Xr mt 1
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command. When a device corresponding to a particular mode is first
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mounted, The operating parameters for that
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mount session
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are copied from that mode. Further changes to the parameters during the
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session will change those in effect for the session but not those set
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in the operation mode. To change the parameters for an operation mode,
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one must either assign the parameters to the control device, or compile
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them into the
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.Dq Em Rogues Gallery
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table in the driver's source code.
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.Pp
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In addition to the four operating modes mentioned above,
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bits 0 and 1 of the minor number are interpreted as
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.Xr mt 1 .
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.Sh SUB-MODES
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Bits 0 and 1 of the minor number are interpreted as
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.Sq sub-modes .
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The sub-modes differ in the action taken when the device is closed:
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.Bl -tag -width XXXX
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@ -179,24 +94,6 @@ A close will rewind the device. If the tape has been
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written, then a file mark will be written before the rewind is requested.
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On completion of the rewind an unload command will be issued.
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The device is unmounted.
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.It 11
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This is a special mode, known as the
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.Dq control device
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for the mode. Parameters set for the mode while in this sub-mode will
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be remembered from one mount to the next. This allows the system
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administrator to set different characteristics (e.g., density,
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blocksize)
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.\" (and eventually compression)
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on each mode, and have the different modes keep those parameters
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independent of any parameter changes a user may invoke during a single
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mount session. At the completion of the user's mount session, drive
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parameters will revert to those set by the administrator. I/O
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operations cannot be performed on this device/sub-mode. General
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.Xr scsi 4
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ioctls can
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.Em only
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be performed against the control device.
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.El
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.Sh BLOCKING MODES
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.Tn SCSI
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tapes may run in either
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@ -238,8 +135,9 @@ and vice-versa.
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If one requests more blocks than remain in the file, the drive will
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encounter the file mark. Because there is some data to return (unless
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there were no records before the file mark), the read will succeed,
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returning that data, The next read will return immediately with an
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EOF. (As above, if the file mark is never read, it remains for the next process to read if in no-rewind mode.)
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returning that data, The next read will return immediately with a value
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of 0. (As above, if the file mark is never read, it remains for the next
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process to read if in no-rewind mode.)
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.El
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.Sh FILE MARK HANDLING
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The handling of file marks on write is automatic. If the user has
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@ -255,148 +153,47 @@ last file is read. These devices include the QIC family of devices.
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(It might be that this set of devices is the same set as that of fixed
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block devices. This has not been determined yet, and they are treated
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as separate behaviors by the driver at this time.)
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.Sh KERNEL CONFIGURATION
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Because different tape drives behave differently, there is a mechanism
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within the source to
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.Nm
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to quickly and conveniently recognize and deal
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with brands and models of drive that have special requirements.
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.Pp
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There is a table (called the
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.Dq Em Rogues Gallery )
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in which the identification
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strings of known errant drives can be stored. Alongside each is
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a set of flags that allows the setting of densities and blocksizes for each
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of the four modes, along with a set of `QUIRK' flags that can be
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used to enable or disable sections of code within the driver if a particular
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drive is recognized.
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.Sh IOCTLS
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The following
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.Xr ioctl 2
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calls apply to
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.Tn SCSI
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tapes. Some also apply to other tapes. They are defined
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in the header file
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.Aq Pa /sys/mtio.h .
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.\"
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.\" Almost all of this discussion belongs in a separate mt(4)
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.\" manual page, since it is common to all magnetic tapes.
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.\"
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.Pp
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.Bl -tag -width MTIOCEEOT
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.It Dv MTIOCGET
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.Pq Li "struct mtget"
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Retrieve the status and parameters of the tape.
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.It Dv MTIOCTOP
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.Pq Li "struct mtop"
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Perform a multiplexed operation. The argument structure is as follows:
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.Bd -literal -offset indent
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struct mtop {
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short mt_op;
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daddr_t mt_count;
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};
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.Ed
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.Pp
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The following operation values are defined for
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.Va mt_op :
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.Bl -tag -width MTSELDNSTY
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.It Dv MTWEOF
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Write
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.Va mt_count
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end of file marks at the present head position.
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.It Dv MTFSF
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Skip over
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.Va mt_count
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file marks. Leave the head on the EOM side of the last skipped
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file mark.
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.It Dv MTBSF
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Skip
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.Em backwards
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over
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.Va mt_count
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file marks. Leave the head on the BOM (beginning of media)
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side of the last skipped file mark.
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.It Dv MTFSR
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Skip forwards over
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.Va mt_count
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records.
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.It Dv MTBSR
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Skip backwards over
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.Va mt_count
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records.
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.It Dv MTREW
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Rewind the device to the beginning of the media.
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.It Dv MTOFFL
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Rewind the media (and, if possible, eject). Even if the device cannot
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eject the media it will often no longer respond to normal requests.
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.It Dv MTNOP
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No-op; set status only.
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.It Dv MTCACHE
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Enable controller buffering.
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.It Dv MTNOCACHE
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Disable controller buffering.
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.It Dv MTSETBSIZ
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Set the blocksize to use for the device/mode. If the device is capable of
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variable blocksize operation, and the blocksize is set to 0, then the drive
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will be driven in variable mode. This parameter is in effect for the present
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mount session only, unless set on the control device.
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.It Dv MTSETDNSTY
|
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Set the density value (see
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.Xr mt 1 )
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to use when running in the mode opened (minor bits 2 and 3).
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This parameter is in effect for the present
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mount session only, unless set on the control device.
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.El
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.It Dv MTIOCIEOT
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Set end-of-tape processing (not presently supported for
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.Nm
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devices).
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.It Dv MTIOCEEOT
|
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Set end-of-tape processing (not presently supported for
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.Nm
|
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devices).
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.El
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.Pp
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In addition, the
|
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.Nm
|
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driver will allow the use of any of the general
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.Xr scsi 4
|
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.Fn ioctl
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commands, on the control device only.
|
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The
|
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.Nm sa
|
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driver supports all of the ioctls of
|
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.Xr mtio 4 .
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.Sh FILES
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.Bl -tag -width /dev/[n][e]rst[0-9].[0-3] -compact
|
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.It Pa /dev/[n][e]rst[0-9].[0-3]
|
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.Bl -tag -width /dev/[n][e]rsa[0-9] -compact
|
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.It Pa /dev/[n][e]rsa[0-9]
|
||||
general form:
|
||||
.It Pa /dev/rst0.0
|
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Mode 0, rewind on close
|
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.It Pa /dev/nrst0.2
|
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Mode 2, No rewind on close
|
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.It Pa /dev/erst0.3
|
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Mode 3, Eject on close (if capable)
|
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.It Pa /dev/rst0
|
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Another name for rst0.0
|
||||
.It Pa /dev/nrst0
|
||||
Another name for nrst0.0
|
||||
.It Pa /dev/st0ctl.0
|
||||
Parameters set to this device become the default parameters for [en]rst0.0
|
||||
.It Pa /dev/st0ctl.1
|
||||
Parameters set to this device become the default parameters for [en]rst0.1
|
||||
.It Pa /dev/st0ctl.2
|
||||
Parameters set to this device become the default parameters for [en]rst0.2
|
||||
.It Pa /dev/st0ctl.3
|
||||
Parameters set to this device become the default parameters for [en]rst0.3
|
||||
.El
|
||||
.It Pa /dev/rsa0
|
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Rewind on close
|
||||
.It Pa /dev/nrsa0
|
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No rewind on close
|
||||
.It Pa /dev/erst0
|
||||
Eject on close (if capable)
|
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.Sh BUGS
|
||||
This driver lacks many of the hacks required to deal with older devices.
|
||||
Many older
|
||||
.Tn SCSI-1
|
||||
devices may not work properly with this driver yet.
|
||||
.Pp
|
||||
The device node interface for different tape formats and modes should
|
||||
be rethought after considering the strategies employed by other vendors.
|
||||
.Pp
|
||||
Support for fast indexing and tape status reporting is lacking.
|
||||
.Sh DIAGNOSTICS
|
||||
None.
|
||||
.Sh SEE ALSO
|
||||
.Xr mt 1 ,
|
||||
.Xr scsi 4 ,
|
||||
.Xr st 9
|
||||
.Xr sa 9
|
||||
.Sh HISTORY
|
||||
This
|
||||
.Nm
|
||||
driver was originally written for
|
||||
The
|
||||
.Nm sa
|
||||
driver was written for the
|
||||
.Tn CAM
|
||||
.Tn SCSI
|
||||
subsystem by Justin T. Gibbs and Kenneth Merry.
|
||||
Many ideas were gleaned from the
|
||||
.Nm st
|
||||
device driver written and ported from
|
||||
.Tn Mach
|
||||
2.5, and was ported to
|
||||
.Tn FreeBSD
|
||||
2.5
|
||||
by Julian Elischer.
|
||||
|
||||
@ -23,255 +23,19 @@
|
||||
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||||
.\" SUCH DAMAGE.
|
||||
.\"
|
||||
.\" $Id: sd.4,v 1.10 1997/02/22 13:24:42 peter Exp $
|
||||
.\" $Id: sd.4,v 1.11 1997/04/01 04:04:09 jdp Exp $
|
||||
.\"
|
||||
.Dd January 18, 1996
|
||||
.Dd October 15, 1998
|
||||
.Dt SD 4
|
||||
.Os FreeBSD
|
||||
.Sh NAME
|
||||
.Nm sd
|
||||
.Nd SCSI disk driver
|
||||
.Sh SYNOPSIS
|
||||
.Cd disk sd
|
||||
.Cd disk sd1 at scbus0 target 4 lun 0
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Nm sd
|
||||
driver provides support for a
|
||||
.Tn SCSI
|
||||
disk. It allows the disk
|
||||
to be divided up into a set of pseudo devices called
|
||||
.Em partitions .
|
||||
In general the interfaces are similar to those described by
|
||||
.Xr wd 4 .
|
||||
.Pp
|
||||
Where the
|
||||
.Xr wd 4
|
||||
device has a fairly low level interface to the system,
|
||||
.Tn SCSI
|
||||
devices have a much higher level interface and talk to the system via
|
||||
a
|
||||
.Tn SCSI
|
||||
host adapter
|
||||
(e.g.,
|
||||
.Xr ahc 4 ) .
|
||||
A
|
||||
.Tn SCSI
|
||||
adapter must also be separately configured into the system
|
||||
before a
|
||||
.Tn SCSI
|
||||
disk can be configured.
|
||||
.Pp
|
||||
When the
|
||||
.Tn SCSI
|
||||
adapter is probed during boot, the
|
||||
.Tn SCSI
|
||||
bus is scanned for devices. Any devices found which answer as
|
||||
.Sq Em Direct
|
||||
type devices will be attached to the
|
||||
.Nm
|
||||
driver has been replaced by the
|
||||
.Xr da 4
|
||||
driver.
|
||||
In
|
||||
.Tn FreeBSD
|
||||
releases prior to 2.1, the first found was attached as
|
||||
.Li sd0 ,
|
||||
the second
|
||||
.Li sd1 ,
|
||||
and so on.
|
||||
Beginning in
|
||||
.Fx 2.1
|
||||
it became possible to lock down the assignment of
|
||||
devices on the
|
||||
.Tn SCSI
|
||||
bus to particular units of the
|
||||
.Nm
|
||||
device; refer to
|
||||
.Xr scsi 4
|
||||
for details on kernel configuration.
|
||||
.Sh PARTITIONING
|
||||
The
|
||||
.Nm
|
||||
driver allows the disk to have two levels of partitioning.
|
||||
One layer, called the
|
||||
.Dq slice layer ,
|
||||
is used to separate the
|
||||
.Tn FreeBSD
|
||||
areas of the disk from areas used by other operating systems.
|
||||
The second layer is the native
|
||||
.Bx 4.4
|
||||
partitioning scheme,
|
||||
.Xr disklabel 5 ,
|
||||
which is used to subdivide the
|
||||
.Tn FreeBSD
|
||||
slices into areas for individual filesystems and swap spaces.
|
||||
For more information, see
|
||||
.Xr fdisk 8
|
||||
and
|
||||
.Xr disklabel 8 ,
|
||||
respectively.)
|
||||
.Pp
|
||||
If an uninitialized disk is opened, the slice table will be
|
||||
initialized with a fictitious
|
||||
.Tn FreeBSD
|
||||
slice spanning the entire disk. Similarly, if an uninitialized
|
||||
(or
|
||||
.No non- Ns Tn FreeBSD )
|
||||
slice is opened, its disklabel will be initialized with parameters returned
|
||||
by the drive and a single
|
||||
.Sq Li c
|
||||
partition encompassing the entire slice.
|
||||
.Sh KERNEL CONFIGURATION
|
||||
It is only necessary to explicitly configure one
|
||||
.Nm
|
||||
device; data structures are dynamically allocated as disks are found
|
||||
on the
|
||||
.Tn SCSI
|
||||
bus.
|
||||
.Sh IOCTLS
|
||||
The following
|
||||
.Xr ioctl 2
|
||||
calls apply to
|
||||
.Tn SCSI
|
||||
disks as well as to other disks. They are defined in the header file
|
||||
.Aq Pa sys/disklabel.h .
|
||||
.Pp
|
||||
.Bl -tag -width DIOCSDINFO
|
||||
.It Dv DIOCSBAD
|
||||
Usually used to set up a bad-block mapping system on the disk.
|
||||
.Tn SCSI
|
||||
drive incorporate their own bad-block mapping so this command is not
|
||||
implemented.
|
||||
.It Dv DIOCGDINFO
|
||||
Read, from the kernel, the in-core copy of the disklabel for the
|
||||
drive. This may be a fictitious disklabel if the drive has never
|
||||
been initialized, in which case it will contain information read
|
||||
from the
|
||||
.Tn SCSI
|
||||
inquiry commands.
|
||||
.It Dv DIOCSDINFO
|
||||
Give the driver a new disklabel to use. The driver
|
||||
.Em will not
|
||||
write the new
|
||||
disklabel to the disk.
|
||||
.It Dv DIOCWLABEL
|
||||
Enable or disable the driver's software
|
||||
write protect of the disklabel on the disk.
|
||||
.It Dv DIOCWDINFO
|
||||
Give the driver a new disklabel to use. The driver
|
||||
.Em will
|
||||
write the new disklabel to the disk.
|
||||
.El
|
||||
.Pp
|
||||
In addition, the
|
||||
.Xr scsi 4
|
||||
general
|
||||
.Fn ioctl
|
||||
commands may be used with the
|
||||
.Nm
|
||||
driver, but only against the
|
||||
.Sq Li c
|
||||
(whole disk) partition.
|
||||
.Sh NOTES
|
||||
If a removable device is attached to the
|
||||
.Nm
|
||||
driver, then the act of changing the media will invalidate the
|
||||
disklabel and information held within the kernel. To avoid
|
||||
corruption, all accesses to the device will be discarded until there
|
||||
are no more open file descriptors referencing the device. During this
|
||||
period, all new open attempts will be rejected. When no more open
|
||||
file descriptors reference the device, the first next open will load a
|
||||
new set of parameters (including disklabel) for the drive.
|
||||
.Sh FILES
|
||||
.Bl -tag -width /dev/rsdXXXXX -compact
|
||||
.It Pa /dev/rsd Ns Ar u
|
||||
raw mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
accessed as an unpartitioned device
|
||||
.Sm off
|
||||
.It Pa /dev/sd Ar u Pa s Ar n
|
||||
.Sm on
|
||||
block mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
slice
|
||||
.Ar n ,
|
||||
accessed as an unpartitioned device
|
||||
.Sm off
|
||||
.It Pa /dev/rsd Ar u Pa s Ar n
|
||||
.Sm on
|
||||
raw mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
slice
|
||||
.ar n ,
|
||||
accessed as an unpartitioned device
|
||||
.It Pa /dev/sd Ns Ar u Ns Ar p
|
||||
block mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
first
|
||||
.Tn FreeBSD
|
||||
slice, partition
|
||||
.Ar p
|
||||
.It Pa /dev/rsd Ns Ar u Ns Ar p
|
||||
raw mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
first
|
||||
.Tn FreeBSD
|
||||
slice, partition
|
||||
.Ar p
|
||||
.Sm off
|
||||
.It Xo
|
||||
.Pa /dev/sd
|
||||
.Ar u
|
||||
.Pa s
|
||||
.Ar n
|
||||
.Ar p
|
||||
.Xc
|
||||
.Sm on
|
||||
block mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
.No Ar n Ns th
|
||||
slice, partition
|
||||
.Ar p
|
||||
.Sm off
|
||||
.It Xo
|
||||
.Pa /dev/rsd
|
||||
.Ar u
|
||||
.Pa s
|
||||
.Ar n
|
||||
.Ar p
|
||||
.Xc
|
||||
raw mode
|
||||
.Tn SCSI
|
||||
disk unit
|
||||
.Ar u ,
|
||||
.No Ar n Ns th
|
||||
slice, partition
|
||||
.Ar p
|
||||
.El
|
||||
.Sh DIAGNOSTICS
|
||||
None.
|
||||
.Sh SEE ALSO
|
||||
.Xr wd 4 ,
|
||||
.Xr disklabel 5 ,
|
||||
.Xr disklabel 8 ,
|
||||
.Xr fdisk 8 ,
|
||||
.Xr sd 9
|
||||
.Sh HISTORY
|
||||
The
|
||||
.Nm
|
||||
driver was originally written for
|
||||
.Tn Mach
|
||||
2.5, and was ported to
|
||||
.Tn FreeBSD
|
||||
by Julian Elischer. Support for slices was written by Bruce Evans.
|
||||
.Xr da 4
|
||||
|
||||
@ -23,380 +23,19 @@
|
||||
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||||
.\" SUCH DAMAGE.
|
||||
.\"
|
||||
.\" $Id$
|
||||
.\" $Id: st.4,v 1.11 1997/03/07 02:49:34 jmg Exp $
|
||||
.\"
|
||||
.Dd January 17, 1996
|
||||
.Dd October 15, 1998
|
||||
.Dt ST 4
|
||||
.Os FreeBSD
|
||||
.Sh NAME
|
||||
.Nm st
|
||||
.Nd SCSI tape driver
|
||||
.Sh SYNOPSIS
|
||||
.Cd tape st
|
||||
.Cd device st1 at scbus0 target 4 lun 0
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Nm
|
||||
driver provides support for a
|
||||
.Tn SCSI
|
||||
tape. It allows the tape
|
||||
to be run in up to four different modes depending on minor numbers
|
||||
and supports several different `sub-modes'.
|
||||
The device can have both a
|
||||
.Em raw
|
||||
interface
|
||||
and a
|
||||
.Em block
|
||||
interface; however, only the raw interface is usually used (or recommended).
|
||||
In general the interfaces are similar to those described by
|
||||
.Xr wt 4
|
||||
or
|
||||
.Xr mt 4 .
|
||||
.Pp
|
||||
Where the
|
||||
.Xr wt 4
|
||||
device has a fairly low level interface to the system,
|
||||
.Tn SCSI
|
||||
devices have a much higher level interface and talk to the system via
|
||||
a
|
||||
.Tn SCSI
|
||||
adapter and a
|
||||
.Tn SCSI
|
||||
adapter driver
|
||||
(e.g.,
|
||||
.Xr ahc 4 ) .
|
||||
A
|
||||
.Tn SCSI
|
||||
adapter must also be separately configured into the system
|
||||
before a
|
||||
.Tn SCSI
|
||||
tape can be configured.
|
||||
.Pp
|
||||
As the
|
||||
.Tn SCSI
|
||||
adapter is probed during boot, the
|
||||
.Tn SCSI
|
||||
bus is scanned for devices. Any devices found which answer as
|
||||
.Sq Em Sequential
|
||||
type devices will be attached to the
|
||||
.Nm
|
||||
.Nm st
|
||||
driver has been replaced by the
|
||||
.Xr sa 4
|
||||
driver.
|
||||
In
|
||||
.Tn FreeBSD
|
||||
releases prior to 2.1, the first found is attached as
|
||||
.Em st0
|
||||
and the next,
|
||||
.Em st1 ,
|
||||
etc.
|
||||
Beginning in
|
||||
.Fx 2.1
|
||||
it is possible to specify what
|
||||
.Nm
|
||||
unit a device should
|
||||
come on line as; refer to
|
||||
.Xr scsi 4
|
||||
for details on kernel configuration.
|
||||
.Sh MOUNT SESSIONS
|
||||
The
|
||||
.Nm
|
||||
driver is based around the concept of a
|
||||
.Dq Em mount session ,
|
||||
which is defined as the period between the time that a tape is
|
||||
mounted, and the time when it is unmounted. Any parameters set during
|
||||
a mount session remain in effect for the remainder of the session or
|
||||
until replaced. The tape can be unmounted, bringing the session to a
|
||||
close in several ways. These include:
|
||||
.Bl -enum
|
||||
.It
|
||||
Closing an `unmount device',
|
||||
referred to as sub-mode 00 below. An example is
|
||||
.Pa /dev/rst0 .
|
||||
.It
|
||||
Using the MTOFFL
|
||||
.Xr ioctl 2
|
||||
command, reachable through the
|
||||
.Sq Cm offline
|
||||
command of
|
||||
.Xr st 1 .
|
||||
.It
|
||||
Opening a different mode will implicitly unmount the tape, thereby closing
|
||||
off the mode that was previously mounted. All parameters will be loaded
|
||||
freshly from the new mode. (See below for more on modes.)
|
||||
.El
|
||||
.Pp
|
||||
Parameters that are required to last across the unmounting of a tape
|
||||
should be set on the control device. This is sub-mode 3 (see below) and is
|
||||
reached through a file with a name of the form
|
||||
.Sm off
|
||||
.No Xo
|
||||
.Pa /dev/st
|
||||
.Ar Y
|
||||
.Pa ctl.
|
||||
.Ar X
|
||||
.Xc ,
|
||||
.Sm on
|
||||
where
|
||||
.Ar Y
|
||||
is the drive number and
|
||||
.Ar X
|
||||
is the mode number.
|
||||
.Sh MODES AND SUB-MODES
|
||||
There are four
|
||||
.Sq operation
|
||||
modes. These are controlled by bits 2 and 3 of the minor number and
|
||||
are designed to allow users to easily read and write different formats
|
||||
of tape on devices that allow multiple formats. The parameters for
|
||||
each mode can be set individually by hand with the
|
||||
.Xr mt 1
|
||||
command. When a device corresponding to a particular mode is first
|
||||
mounted, The operating parameters for that
|
||||
mount session
|
||||
are copied from that mode. Further changes to the parameters during the
|
||||
session will change those in effect for the session but not those set
|
||||
in the operation mode. To change the parameters for an operation mode,
|
||||
one must either assign the parameters to the control device, or compile
|
||||
them into the
|
||||
.Dq Em Rogues Gallery
|
||||
table in the driver's source code.
|
||||
.Pp
|
||||
In addition to the four operating modes mentioned above,
|
||||
bits 0 and 1 of the minor number are interpreted as
|
||||
.Sq sub-modes .
|
||||
The sub-modes differ in the action taken when the device is closed:
|
||||
.Bl -tag -width XXXX
|
||||
.It 00
|
||||
A close will rewind the device; if the tape has been
|
||||
written, then a file mark will be written before the rewind is requested.
|
||||
The device is unmounted.
|
||||
.It 01
|
||||
A close will leave the tape mounted.
|
||||
If the tape was written to, a file mark will be written.
|
||||
No other head positioning takes place.
|
||||
Any further reads or writes will occur directly after the
|
||||
last read, or the written file mark.
|
||||
.It 10
|
||||
A close will rewind the device. If the tape has been
|
||||
written, then a file mark will be written before the rewind is requested.
|
||||
On completion of the rewind an unload command will be issued.
|
||||
The device is unmounted.
|
||||
.It 11
|
||||
This is a special mode, known as the
|
||||
.Dq control device
|
||||
for the mode. Parameters set for the mode while in this sub-mode will
|
||||
be remembered from one mount to the next. This allows the system
|
||||
administrator to set different characteristics (e.g., density,
|
||||
blocksize)
|
||||
.\" (and eventually compression)
|
||||
on each mode, and have the different modes keep those parameters
|
||||
independent of any parameter changes a user may invoke during a single
|
||||
mount session. At the completion of the user's mount session, drive
|
||||
parameters will revert to those set by the administrator. I/O
|
||||
operations cannot be performed on this device/sub-mode. General
|
||||
.Xr scsi 4
|
||||
ioctls can
|
||||
.Em only
|
||||
be performed against the control device.
|
||||
.El
|
||||
.Sh BLOCKING MODES
|
||||
.Tn SCSI
|
||||
tapes may run in either
|
||||
.Sq Em variable
|
||||
or
|
||||
.Sq Em fixed
|
||||
block-size modes. Most
|
||||
.Tn QIC Ns -type
|
||||
devices run in fixed block-size mode, where most nine-track tapes and
|
||||
many new cartridge formats allow variable block-size. The difference
|
||||
between the two is as follows:
|
||||
.Bl -inset
|
||||
.It Variable block-size:
|
||||
Each write made to the device results in a single logical record
|
||||
written to the tape. One can never read or write
|
||||
.Em part
|
||||
of a record from tape (though you may request a larger block and read
|
||||
a smaller record); nor can one read multiple blocks. Data from a
|
||||
single write is therefore read by a single read. The block size used
|
||||
may be any value supported by the device, the
|
||||
.Tn SCSI
|
||||
adapter and the system (usually between 1 byte and 64 Kbytes,
|
||||
sometimes more).
|
||||
.Pp
|
||||
When reading a variable record/block from the tape, the head is
|
||||
logically considered to be immediately after the last item read,
|
||||
and before the next item after that. If the next item is a file mark,
|
||||
but it was never read, then the next
|
||||
process to read will immediately hit the file mark and receive an end-of-file notification.
|
||||
.It Fixed block-size
|
||||
Data written by the user is passed to the tape as a succession of
|
||||
fixed size blocks. It may be contiguous in memory, but it is
|
||||
considered to be a series of independent blocks. One may never write
|
||||
an amount of data that is not an exact multiple of the blocksize. One
|
||||
may read and write the same data as a different set of records, In
|
||||
other words, blocks that were written together may be read separately,
|
||||
and vice-versa.
|
||||
.Pp
|
||||
If one requests more blocks than remain in the file, the drive will
|
||||
encounter the file mark. Because there is some data to return (unless
|
||||
there were no records before the file mark), the read will succeed,
|
||||
returning that data, The next read will return immediately with an
|
||||
EOF. (As above, if the file mark is never read, it remains for the next process to read if in no-rewind mode.)
|
||||
.El
|
||||
.Sh FILE MARK HANDLING
|
||||
The handling of file marks on write is automatic. If the user has
|
||||
written to the tape, and has not done a read since the last write,
|
||||
then a file mark will be written to the tape when the device is
|
||||
closed. If a rewind is requested after a write, then the driver
|
||||
assumes that the last file on the tape has been written, and ensures
|
||||
that there are two file marks written to the tape. The exception to
|
||||
this is that there seems to be a standard (which we follow, but don't
|
||||
understand why) that certain types of tape do not actually write two
|
||||
file marks to tape, but when read, report a `phantom' file mark when the
|
||||
last file is read. These devices include the QIC family of devices.
|
||||
(It might be that this set of devices is the same set as that of fixed
|
||||
block devices. This has not been determined yet, and they are treated
|
||||
as separate behaviors by the driver at this time.)
|
||||
.Sh KERNEL CONFIGURATION
|
||||
Because different tape drives behave differently, there is a mechanism
|
||||
within the source to
|
||||
.Nm
|
||||
to quickly and conveniently recognize and deal
|
||||
with brands and models of drive that have special requirements.
|
||||
.Pp
|
||||
There is a table (called the
|
||||
.Dq Em Rogues Gallery )
|
||||
in which the identification
|
||||
strings of known errant drives can be stored. Alongside each is
|
||||
a set of flags that allows the setting of densities and blocksizes for each
|
||||
of the four modes, along with a set of `QUIRK' flags that can be
|
||||
used to enable or disable sections of code within the driver if a particular
|
||||
drive is recognized.
|
||||
.Sh IOCTLS
|
||||
The following
|
||||
.Xr ioctl 2
|
||||
calls apply to
|
||||
.Tn SCSI
|
||||
tapes. Some also apply to other tapes. They are defined
|
||||
in the header file
|
||||
.Aq Pa /sys/mtio.h .
|
||||
.\"
|
||||
.\" Almost all of this discussion belongs in a separate mt(4)
|
||||
.\" manual page, since it is common to all magnetic tapes.
|
||||
.\"
|
||||
.Pp
|
||||
.Bl -tag -width MTIOCEEOT
|
||||
.It Dv MTIOCGET
|
||||
.Pq Li "struct mtget"
|
||||
Retrieve the status and parameters of the tape.
|
||||
.It Dv MTIOCTOP
|
||||
.Pq Li "struct mtop"
|
||||
Perform a multiplexed operation. The argument structure is as follows:
|
||||
.Bd -literal -offset indent
|
||||
struct mtop {
|
||||
short mt_op;
|
||||
daddr_t mt_count;
|
||||
};
|
||||
.Ed
|
||||
.Pp
|
||||
The following operation values are defined for
|
||||
.Va mt_op :
|
||||
.Bl -tag -width MTSELDNSTY
|
||||
.It Dv MTWEOF
|
||||
Write
|
||||
.Va mt_count
|
||||
end of file marks at the present head position.
|
||||
.It Dv MTFSF
|
||||
Skip over
|
||||
.Va mt_count
|
||||
file marks. Leave the head on the EOM side of the last skipped
|
||||
file mark.
|
||||
.It Dv MTBSF
|
||||
Skip
|
||||
.Em backwards
|
||||
over
|
||||
.Va mt_count
|
||||
file marks. Leave the head on the BOM (beginning of media)
|
||||
side of the last skipped file mark.
|
||||
.It Dv MTFSR
|
||||
Skip forwards over
|
||||
.Va mt_count
|
||||
records.
|
||||
.It Dv MTBSR
|
||||
Skip backwards over
|
||||
.Va mt_count
|
||||
records.
|
||||
.It Dv MTREW
|
||||
Rewind the device to the beginning of the media.
|
||||
.It Dv MTOFFL
|
||||
Rewind the media (and, if possible, eject). Even if the device cannot
|
||||
eject the media it will often no longer respond to normal requests.
|
||||
.It Dv MTNOP
|
||||
No-op; set status only.
|
||||
.It Dv MTCACHE
|
||||
Enable controller buffering.
|
||||
.It Dv MTNOCACHE
|
||||
Disable controller buffering.
|
||||
.It Dv MTSETBSIZ
|
||||
Set the blocksize to use for the device/mode. If the device is capable of
|
||||
variable blocksize operation, and the blocksize is set to 0, then the drive
|
||||
will be driven in variable mode. This parameter is in effect for the present
|
||||
mount session only, unless set on the control device.
|
||||
.It Dv MTSETDNSTY
|
||||
Set the density value (see
|
||||
.Xr mt 1 )
|
||||
to use when running in the mode opened (minor bits 2 and 3).
|
||||
This parameter is in effect for the present
|
||||
mount session only, unless set on the control device.
|
||||
.El
|
||||
.It Dv MTIOCIEOT
|
||||
Set end-of-tape processing (not presently supported for
|
||||
.Nm
|
||||
devices).
|
||||
.It Dv MTIOCEEOT
|
||||
Set end-of-tape processing (not presently supported for
|
||||
.Nm
|
||||
devices).
|
||||
.El
|
||||
.Pp
|
||||
In addition, the
|
||||
.Nm
|
||||
driver will allow the use of any of the general
|
||||
.Xr scsi 4
|
||||
.Fn ioctl
|
||||
commands, on the control device only.
|
||||
.Sh FILES
|
||||
.Bl -tag -width /dev/[n][e]rst[0-9].[0-3] -compact
|
||||
.It Pa /dev/[n][e]rst[0-9].[0-3]
|
||||
general form:
|
||||
.It Pa /dev/rst0.0
|
||||
Mode 0, rewind on close
|
||||
.It Pa /dev/nrst0.2
|
||||
Mode 2, No rewind on close
|
||||
.It Pa /dev/erst0.3
|
||||
Mode 3, Eject on close (if capable)
|
||||
.It Pa /dev/rst0
|
||||
Another name for rst0.0
|
||||
.It Pa /dev/nrst0
|
||||
Another name for nrst0.0
|
||||
.It Pa /dev/st0ctl.0
|
||||
Parameters set to this device become the default parameters for [en]rst0.0
|
||||
.It Pa /dev/st0ctl.1
|
||||
Parameters set to this device become the default parameters for [en]rst0.1
|
||||
.It Pa /dev/st0ctl.2
|
||||
Parameters set to this device become the default parameters for [en]rst0.2
|
||||
.It Pa /dev/st0ctl.3
|
||||
Parameters set to this device become the default parameters for [en]rst0.3
|
||||
.El
|
||||
.Sh DIAGNOSTICS
|
||||
None.
|
||||
.Sh SEE ALSO
|
||||
.Xr mt 1 ,
|
||||
.Xr scsi 4 ,
|
||||
.Xr st 9
|
||||
.Sh HISTORY
|
||||
This
|
||||
.Nm
|
||||
driver was originally written for
|
||||
.Tn Mach
|
||||
2.5, and was ported to
|
||||
.Tn FreeBSD
|
||||
by Julian Elischer.
|
||||
.Xr sa 4
|
||||
|
||||
Loading…
Reference in New Issue
Block a user