'\" te
.\" Copyright (c) 2011, 2012, Oracle and/or its affiliates. All rights reserved.
.TH devchassis 7FS "23 Apr 2012" "SunOS 5.11" "File Systems"
.SH NAME
devchassis \- device name file system
.SH DESCRIPTION
.sp
.LP
The chassis subdirectory of the \fB/dev\fR \fBdevfs\fR(7FS) file system provides a location-oriented name space. The \fB/dev/chassis\fR name space is maintained by the \fBdevchassisd\fR(1M) \fBsmf\fR service. The \fB/dev/chassis\fR name space is structured by \fIchassis\fR, \fIreceptacle\fR, and current \fIoccupant\fR. Within the \fIchassis/receptacle\fR name space, the current occupant is maintained as a dynamic symlink into the \fB/devices\fR file system.
.sp
.in +2
.nf
/dev/chassis/
  <chassis-name>.<chassis-serial>[[/receptable-name]*
     [/<occupant-type> -> /devices/...]]
.fi
.in -2
.sp

.sp
.LP
An empty receptacle is represented as an empty directory.
.sp
.LP
If an \fBfmadm\fR(1M)\(emmanaged \fI<alias-id>\fR exists, then the \fI<chassis-name>\fR\&.\fI<chassis-serial>\fR is replaced by a managed \fI<alias-id>\fR\&. A managed \fI<alias-id>\fR can establish the physical location of chassis, like a building, lab, rack, and chassis U-number range inside the rack.
.sp
.LP
There is always one well-known \fI<alias-id>\fR associated with internal locations: \fBSYS\fR. This \fI<alias-id>\fR cannot be modified. 
.sp
.LP
A \fI<receptable-name>\fR is associated with chassis silk-screen labeling of receptacles (like disk bays). Multiple \fI<receptacle-name>\fR directories can be used before coming to an occupant symlink.
.sp
.LP
The \fB/dev/chassis\fR name space allows you to administer the machine based on physical location.
.sp
.in +2
.nf
# format /dev/chassis/SYS/HD0/disk

# zpool create tank mirror \e
        /dev/chassis/RACK29.U01-04/DISK_00/disk \e
        /dev/chassis/RACK29.U05-08/DISK_00/disk
.fi
.in -2
.sp

.sp
.LP
\fBfmd\fR(1M) machine topology understanding is required to drive the creation and maintenance of the \fB/dev/chassis\fR name space. If this understanding is lacking, the \fB/dev/chassis\fR name space will be lacking. \fBfmd\fR(1M) and \fBdevchassisd\fR(1M)operation is coordinated using the contents of \fB/etc/dev/cro_db\fR. This same data file is also used by the \fBcroinfo\fR(1M) utility.
.SH FILES
.sp
.ne 2
.mk
.na
\fB\fB/dev/chassis\fR\fR
.ad
.RS 19n
.rt  
Directory under the \fB/dev\fR file system mount point that provides, when possible, a location-oriented device name space.
.RE

.sp
.ne 2
.mk
.na
\fB\fB/etc/dev/cro_db\fR\fR
.ad
.RS 19n
.rt  
Data file created by \fBfmd\fR(1M) used to obtain information about chassis, receptacles, and occupants.
.RE

.SH SEE ALSO
.sp
.LP
\fBcroinfo\fR(1M), \fBdevchassisd\fR(1M), \fBfmadm\fR(1M), \fBfmd\fR(1M), \fBdevices\fR(4), \fBdevfs\fR(7FS)
.SH NOTES
.sp
.LP
To prevent stale links, the entire \fB/dev/chassis\fR name space is removed during each boot and reestablished when both \fBfmd\fR(1M) and \fBdevchassisd\fR(1M) are running. If \fBdevchassisd\fR(1M) is not running, the \fB/dev/chassis\fR name space does not exist.
.sp
.LP
Gaps in \fBfmd\fR(1M) topology representation result in gaps in the \fB/dev/chassis\fR name space.