Daemon
A daemon is a process that performs a particular system task.
 

Dataless

Dataless denotes a workstation that has a small disk for the / (root) file system and swap space. It must get its /usr file system (and typically additional file systems) from another system.
 

DCE

Data communications equipment (DCE) refers to RS-232 and serial communications devices. DCE uses pin 2 to receive and pin 3 to transmit. Modems are always DCE.
 
Delimiter
A delimiter is a special character, often a slash or a space, used to separate one string of characters from another.

Density

Density refers to the amount of data that will fit onto media.

Device

A hardware component or "physical device," such as a printer or disk drive, acting as a unit to perform a specific function.

Device Driver

Device drivers are programs that the kernel (operating system software) uses to communicate with devices.

Device File

A device file is a special type of file that the operating system uses to access hardware devices.

df

The df command is used to display the amount of disk space occupied by mounted or unmounted file systems, directories, or resources; the amount of available space; and how much of a file system's total capacity has been used.

dfshares

The dfshares command is used to locate information about resources available to the host through a distributed file system. If dfshares is entered without arguments, all resources currently shared on the local file system are displayed, regardless of file system type.

DHCP

Dynamic Host Configuration Protocol (DHCP) automatically assigns Internet Protocol (IP) addresses to client computers when the client joins the network. This eliminates the need to maintain a static list of addresses for each client. DHCP selects an IP address from a preconfigured pool.

Direct Block

Direct block addressing as used in UNIX systems is an inode field which points to a block containing the file.

Directory

A directory is a location for files and other directories. The Solaris file system or directory structure enables you to create files and directories which can be accessed through a hierarchy of directories.

Disk Controller

A disk controller is a hardware device that acts as an interface between the operating system and the disk device connected to the system.

Disk Label

A disk label is created when the disk is formatted. It is located in the first disk sector, a 512-byte block.

Diskless

A diskless workstation is a workstation that has no hard disk. Users must rely on another system for the programs they need and for file storage space.

Distributed Processing

Distributed processing is a feature of the Solaris computing environment that enables the use of resources across the network.

dmesg

The dmesg command is used to display diagnostic messages about system hardware. If the "-" option is used, the dmesg computes (incrementally) the number of new messages that have been displayed since the last time the dmesg command was run.

DNLC

The Directory Name Lookup Cache (DNLC) associates the name of a file with a . Thus the file can be found on subsequent attempts without searching the directories.

DNS

Domain Name Systems (DNS) provide translations of hostnames into IP addresses. This allows internet communications using only hostnames.

Domain

A domain is the name assigned to a group of systems on a local network that share administrative files. The domain name is required for the network information service database to work properly.

DTE

Data terminal equipment (DTE) refers to RS-232 and serial communications devices. DTE uses pin 2 to transmit and pin 3 to receive.

du

The du command is used to report the number of 512 byte blocks contained in all files and (recursively) directories within each directory and file specified.

Dump Levels

Dump levels are used to determine what data is to be backed up with the ufsdump command. The ufsdump command provides different levels of dumps; level 0 is a full dump, and levels 1 through 9 provide incremental dumps. The ufsdump command can also facilitate multivolume dumps.

Dump Schedule

A dump schedule coordinates the use of tape media so that a minimum number of tapes are used to provide the maximum amount of backup coverage required.

A typical dump schedule starts with a level 0 backup, sometime at the end of the week, followed by incremental dumps on successive days in the week.

For example:


 Monday  Tuesday  Wednesday  Thursday Friday
|-------|--------|----------|--------|------|
|   2   |    2   |    2     |    2   |   0  |
|-------|--------|----------|--------|------|

This schedule has the advantage of requiring only two sets of tapes. On Friday, a level 0 backup stores every file on the file system onto one set of tapes. Then, Monday through Thursday, only the files that have changed or have been created are stored on a second set of tapes. However, if a file is changed on Thursday, and the user wants to restore the file to a previous state, the user can only restore to Wednesday's or the previous Friday's file. This schedule works well for a system that is small and on which not many changes are made during the week.

For a larger file system, with many users changing and creating files, the following schedule might be more appropriate:


 Monday  Tuesday  Wednesday  Thursday Friday
|-------|--------|----------|--------|------|
|   8   |    6   |     6    |    2   |  0   |
|-------|--------|----------|--------|------|

This schedule requires five sets of tapes, but the schedule allows users to change and modify files and back up to any previous day's work if the file is lost.

Dumping

Dumping is the process of copying files and directories for off-line storage.