did(7)						     Sun Cluster Device and Network Interfaces						    did(7)

NAME

       did - user configurable disk id driver

DESCRIPTION

       Note -

	 Beginning  with  the Sun Cluster 3.2 release, Sun Cluster software includes an object-oriented command set. Although Sun Cluster software
	 still supports the original command set, Sun Cluster procedural documentation uses only the object-oriented command set. For more  infor-
	 mation about the object-oriented command set, see the Intro(1CL) man page.

       Disk  ID  (DID)	is  a  user  configurable pseudo device driver that provides access to	underlying disk, tape, and CDROM devices. When the
       device supports unique device ids, multiple paths to a device are determined according to the device id of the  device.	Even  if  multiple
       paths are available with the same device id, only one DID name is given to the actual device.

       In  a  clustered environment, a particular physical device will have the same DID name regardless of its connectivity to more than one host
       or controller.  This, however, is only true of devices that support a global unique device identifier such as physical disks.

       DID maintains parallel directories for each type of device that it manages under /dev/did. The devices in these directories behave the same
       as  their  non-DID  counterparts.  This	includes  maintaining slices for disk and CDROM devices as well as names for different tape device
       behaviors.  Both raw and block device access is also supported for disks by means of /dev/did/rdsk and /dev/did/rdsk.

       At any point in time, I/O is only supported down one path to the device.  No multipathing support is currently available through DID.

       Before a DID device can be used, it must first be initialized by means of the scdidadm(1M) command.

IOCTLS

       The DID driver maintains an admin node as well as nodes for each DID device minor.

       No user ioctls are supported by the admin node.

       The  DKIOCINFO ioctl is supported when called against the DID device nodes such as /dev/did/rdsk/d0s2.

       All other ioctls are passed directly to the driver below.

FILES

       /dev/did/dsk/dnsm		   block disk or CDROM device, where  n is the device number and  m is the slice number

       /dev/did/rdsk/dnsm		   raw disk or CDROM device, where  n is the device number and	m is the slice number

       /dev/did/rmt/n			   tape device , where n is the device number

       /dev/did/admin			   administrative device

       /kernel/drv/did			   driver module

       /kernel/drv/did.conf		   driver configuration file

       /etc/did.conf			   scdidadm configuration file for non-clustered systems

       Cluster Configuration Repository (CCscdidadm(1M) maintains configuration in the CCR for clustered systems

SEE ALSO

       devfsadm(1M), Intro(1CL), cldevice(1CL), scdidadm(1M)

NOTES

       DID creates names for devices in groups, in order to decrease the overhead during device hot-plug.  For disks, device names are created	in
       /dev/did/dsk  and   /dev/did/rdsk  in  groups of 100 disks at a time.  For tapes, device names are created in  /dev/did/rmt in groups of 10
       tapes at a time.  If more devices are added to the cluster  than are handled by the current names, another group will be created.

Sun Cluster 3.2 						   24 April 2001							    did(7)