did(7) Sun Cluster Device and Network Interfaces did(7)
did - user configurable disk id driver
Beginning with the Sun Cluster 3.2 release, Sun Cluster software includes an object-ori-
ented 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 information 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 under-
lying 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 multi-
ple paths are available with the same device id, only one DID name is given to the actual
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
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)
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
All other ioctls are passed directly to the driver below.
/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 num-
ber 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
devfsadm(1M), Intro(1CL), cldevice(1CL), scdidadm(1M)
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)