man pages section 1M: System Administration Commands

tapes(1M)

Name

tapes– creates /dev entries for tape drives attached to the system

Synopsis

/usr/sbin/tapes [-r root_dir]

Description

devfsadm(1M) is now the preferred command for /dev and /devices and should be used instead of tapes.

tapes creates symbolic links in the /dev/rmt directory to the actual tape device special files under the /devices directory tree. tapes searches the kernel device tree to see what tape devices are attached to the system. For each equipped tape drive, the following steps are performed:

The /dev/rmt directory is searched for a /dev/rmt/n entry that is a symbolic link to the /devices special node of the current tape drive. If one is found, this determines the logical controller number of the tape drive.
The rest of the special devices associated with the drive are checked, and incorrect symbolic links are removed and necessary ones added.
If none are found, a new logical controller number is assigned (the lowest-unused number), and new symbolic links are created for all the special devices associated with the drive.

tapes does not remove links to non-existent devices; these must be removed by hand.

tapes is run each time a reconfiguration-boot is performed, or when add_drv(1M) is executed.

Notice to Driver Writers

tapes(1M) considers all devices with the node type DDI_NT_TAPE to be tape devices; these devices must have their minor name created with a specific format. The minor name encodes operational modes for the tape device and consists of an ASCII string of the form [ l,m,h,c,u ][ b ][ n ].

The first character set is used to specify the tape density of the device, and are named low (l), medium (m), high (h), compressed (c), and ultra (u). These specifiers only express a relative density; it is up to the driver to assign specific meanings as needed. For example, 9 track tape devices interpret these as actual bits-per-inch densities, where l means 800 BPI, m means 1600 BPI , and h means 6250 BPI, whereas 4mm DAT tapes defines l as standard format, and m, h, c and u as compressed format. Drivers may choose to implement any or all of these format types.

During normal tape operation (non-BSD behavior), once an EOF mark has been reached, subsequent reads from the tape device return an error. An explicit IOCTL must be issued to space over the EOF mark before the next file can be read. b instructs the device to observe BSD behavior, where reading at EOF will cause the tape device to automatically space over the EOF mark and begin reading from the next file.

n or no-rewind-on-close instructs the driver to not rewind to the beginning of tape when the device is closed. Normal behavior for tape devices is to reposition to BOT when closing. See mtio(7I).

The minor number for tape devices should be created by encoding the device's instance number using the tape macro MTMINOR and ORing in the proper combination of density, BSD behavior, and no-rewind flags. See mtio(7I).

To prevent tapes from attempting to automatically generate links for a device, drivers must specify a private node type and refrain from using the node type string DDI_NT_TAPE when callingddi_create_minor_node(9F).

Options

The following options are supported:

-r root_dir: Causes tapes to presume that the /dev/rmt directory tree is found under root_dir, not directly under /.

Errors

If tapes finds entries of a particular logical controller linked to different physical controllers, it prints an error message and exits without making any changes to the /dev directory, since it cannot determine which of the two alternative logical to physical mappings is correct. The links should be manually corrected or removed before another reconfiguration boot is performed.

Examples

Example 1 Creating Tape Device Nodes From Within the Driver's `attach()` Function

This example demonstrates creating tape device nodes from within the xktape driver's attach(9E) function.

#include <sys/mtio.h>
struct tape_minor_info {
    char *minor_name;
    int   minor_mode;
}; 
/*  
 * create all combinations of logical tapes
*/ 
static struct tape_minor_info example_tape[] = {
   {"",    0},                     /* default tape */
   {"l",   MT_DENSITY1},
   {"lb",  MT_DENSITY1 | MT_BSD},
   {"lbn", MT_DENSITY1 | MT_BSD | MT_NOREWIND},
   {"m",   MT_DENSITY2},
   {"mb",  MT_DENSITY2 | MT_BSD},
   {"mbn", MT_DENSITY2 | MT_BSD | MT_NOREWIND},
   {"h",   MT_DENSITY3},
   {"hb",  MT_DENSITY3 | MT_BSD},
   {"hbn", MT_DENSITY3 | MT_BSD | MT_NOREWIND},
   {"c",   MT_DENSITY4},
   {"cb",  MT_DENSITY4 | MT_BSD},
   {"cbn", MT_DENSITY4| MT_BSD | MT_NOREWIND},
   {NULL,  0}, 
};   

int 
xktapeattach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
   int instance;
   struct tape_minor_info *mdp;
      /* other stuff in attach... */
   instance = ddi_get_instance(dip);

   for (mdp = example_tape; mdp->minor_name != NULL; mdp++) {
            ddi_create_minor_node(dip, mdp->minor_name, S_IFCHR,
                 (MTMINOR(instance) | mdp->minor_mode), DDI_NT_TAPE, 0);
 }

Installing the xktape driver on a Sun Fire 4800, with the driver controlling a SCSI tape (target 4 attached to an isp(7D) SCSI HBA) and performing a reconfiguration-boot creates the following special files in /devices.

# ls -l /devices/ssm@0,0/pci@18,700000/pci@1/SUNW,isptwo@4
crw-rw-rw-   1 root sys   33,136 Aug 29 00:02  xktape@4,0:
crw-rw-rw-   1 root sys   33,200 Aug 29 00:02  xktape@4,0:b
crw-rw-rw-   1 root sys   33,204 Aug 29 00:02  xktape@4,0:bn
crw-rw-rw-   1 root sys   33,152 Aug 29 00:02  xktape@4,0:c
crw-rw-rw-   1 root sys   33,216 Aug 29 00:02  xktape@4,0:cb
crw-rw-rw-   1 root sys   33,220 Aug 29 00:02  xktape@4,0:cbn
crw-rw-rw-   1 root sys   33,156 Aug 29 00:02  xktape@4,0:cn
crw-rw-rw-   1 root sys   33,144 Aug 29 00:02  xktape@4,0:h
crw-rw-rw-   1 root sys   33,208 Aug 29 00:02  xktape@4,0:hb
crw-rw-rw-   1 root sys   33,212 Aug 29 00:02  xktape@4,0:hbn
crw-rw-rw-   1 root sys   33,148 Aug 29 00:02  xktape@4,0:hn
crw-rw-rw-   1 root sys   33,128 Aug 29 00:02  xktape@4,0:l
crw-rw-rw-   1 root sys   33,192 Aug 29 00:02  xktape@4,0:lb
crw-rw-rw-   1 root sys   33,196 Aug 29 00:02  xktape@4,0:lbn
crw-rw-rw-   1 root sys   33,132 Aug 29 00:02  xktape@4,0:ln
crw-rw-rw-   1 root sys   33,136 Aug 29 00:02  xktape@4,0:m
crw-rw-rw-   1 root sys   33,200 Aug 29 00:02  xktape@4,0:mb
crw-rw-rw-   1 root sys   33,204 Aug 29 00:02  xktape@4,0:mbn
crw-rw-rw-   1 root sys   33,140 Aug 29 00:02  xktape@4,0:mn
crw-rw-rw-   1 root sys   33,140 Aug 29 00:02  xktape@4,0:n

/dev/rmt will contain the logical tape devices (symbolic links to tape devices in /devices).

# ls -l /dev/rmt
/dev/rmt/0    -> ../../devices/[....]/xktape@4,0:
/dev/rmt/0b   -> ../../devices/[....]/xktape@4,0:b
/dev/rmt/0bn  -> ../../devices/[....]/xktape@4,0:bn
/dev/rmt/0c   -> ../../devices/[....]/xktape@4,0:c
/dev/rmt/0cb  -> ../../devices/[....]/xktape@4,0:cb
/dev/rmt/0cbn -> ../../devices/[....]/xktape@4,0:cbn
/dev/rmt/0cn  -> ../../devices/[....]/xktape@4,0:cn
/dev/rmt/0h   -> ../../devices/[....]/xktape@4,0:h
/dev/rmt/0hb  -> ../../devices/[....]/xktape@4,0:hb
/dev/rmt/0hbn -> ../../devices/[....]/xktape@4,0:hbn
/dev/rmt/0hn  -> ../../devices/[....]/xktape@4,0:hn
/dev/rmt/0l   -> ../../devices/[....]/xktape@4,0:l
/dev/rmt/0lb  -> ../../devices/[....]/xktape@4,0:lb
/dev/rmt/0lbn -> ../../devices/[....]/xktape@4,0:lbn
/dev/rmt/0ln  -> ../../devices/[....]/xktape@4,0:ln
/dev/rmt/0m   -> ../../devices/[....]/xktape@4,0:m
/dev/rmt/0mb  -> ../../devices/[....]/xktape@4,0:mb
/dev/rmt/0mbn -> ../../devices/[....]/xktape@4,0:mbn
/dev/rmt/0mn  -> ../../devices/[....]/xktape@4,0:mn
/dev/rmt/0n   -> ../../devices/[....]/xktape@4,0:n

Files

/dev/rmt/*: logical tape devices
/devices/*: tape device nodes

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWcsu

Bugs

tapes silently ignores malformed minor device names.

SunOS 5.10 Last Revised 8 Nov 2002