Application Programming Interface. A set of routines, protocols, and tools used for building software applications.


An entry in the schema that associates a name with a type. For example, the name Doctor may be of type string. Metadata is stored by assigning a value of the appropriate type to an attribute name, and attributes may also be used to create views.


The basic building block of the Sun StorageTek 5800 system. It consists of either 8 or 16 Sun StorageTek 5800 system nodes, 2 Load Balancers, and 1 Service Node.


An application that runs on a personal computer or workstation and relies on a server to perform some operations.


See the Sun StorageTek 5800 system cluster.


Central Processing Unit. The brains of the computer, it is sometimes referred to simply as the processor or central processor. It is where most calculations take place


creation time. The system metadata includes information on the creation time, data length, and data hash.

data object

A stored file associated with an object ID (OID).

data hash

Hashes are used for accessing data or for security. A hash, also called a message digest, is a number generated from a string of text. The hash is substantially smaller than the text itself, and is generated by a formula in such a way that it is extremely unlikely that some other text will produce the same hash value.

disk mask

A current record of disk availability across the cluster.


One of the defined attribute types.


Document Type Definition. It defines the legal building blocks of an XML document. The DTD defines the document structure with a list of legal elements, thus providing an application-independent way of sharing data.

dual star topology

A network topology in which two concentric rings connect each node on a network instead of one network ring that is used in a ring topology. Typically, the secondary ring in a dual-ring topology is redundant and is used as a backup in case the primary ring fails. In these configurations, data moves in opposite directions around the rings. Each ring is independent of the other until the primary ring fails and the two rings are connected to continue the flow of data traffic.

encoding algorithm

A coding formula or set of steps for solving a particular problem. To qualify as an algorithm, the set of rules must be unambiguous and have a clear stopping point.


A piece of a file. Files over a certain size are stored in several chunks or fragments rather than in a single contiguous sequence of bits in one place. The Sun StorageTek 5800 system stores fragments of files across multiple disks and nodes using 5+2 encoding. Thus, when an object of any type (for example, an MP3 binary or a text file) is stored in the Sun StorageTek 5800 system, it is divided into five data fragments and two corresponding parity fragments.

front end

The client portion of a client/server application that requests services across a network from a server, which is sometimes known as the back end.


Field-replaceable unit. Describes any hardware device, or more commonly a part or component of a device or system, that can easily be replaced by a skilled technician without having to send the entire device or system to be repaired. As the name implies, the unit can be replaced in the field (that is, at the user location).


Gigabyte. Represents 2 to the 30th power (1,073,741,824) bytes. One gigabyte is equal to 1,024 megabytes.


HyperText Markup Language. Designed to display data and focus on how data looks. The tags you use to markup HTML documents and the document's structure are predefined, so that you can only use tags that are defined in the HTML standard.


HyperText Transfer Protocol. Underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands.


Extra information about the data object. Describes how and when and by whom a particular set of data was collected, and how the data is formatted. There are two main types of metadata in the Sun StorageTek 5800 system: system and user metadata.


Moving Pictures Experts Group (MPEG), audio layer 3 file. Layer 3 is one of three coding schemes (layer 1, layer 2 and layer 3) for the compression of audio signals.


Network Interface Card. An expansion board inserted into a computer to allow the computer to be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.


A processing location. A node can be a computer or some other device, such as a printer. Every node has a unique network address.


Network Time Protocol. An Internet standard protocol (built on top of TCP/IP) that assures accurate synchronization to the millisecond of computer clock times in a network.


Any item that can be individually selected and manipulated. For example, in object-oriented programming, an object is a self-contained entity that consists of both data and procedures to manipulate the data.


Object ID. A unique identifier for each stored object included in the system metadata.


Version 10 of the Apple Macintosh operating system. It incorporates support for Unix-based applications as well as for those written just for the Macintosh.


A request for information from a database.

Reed-Solomon Encoding Algorithm

Files are protected in the Sun StorageTek 5800 system using the Reed Solomon (RS) encoding algorithm. The RS algorithm is part of a code family that efficiently builds redundancy into a file to guarantee reliability in the face of multiple part failures in the storage system.


Serial ATA. An evolution of the Parallel ATA physical storage interface. SATA is a serial link- a single cable with a minimum of four wires- that creates a point-to-point connection between devices. Transfer rates for SATA begin at 150MBps.


The schema defines the way that the Sun StorageTek 5800 system metadata is structured. It consists of attributes, each of which has a defined type.


Simple Mail Transfer Protocol. A protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP.


A receptacle for a microprocessor or other hardware component.


Having no information about what occurred previously. Most applications maintain state, which means that they remember what you were doing last time you ran the application, as well as remembering all your configuration settings.

The World Wide Web, on the other hand, is intrinsically stateless because each request for a new Web page is processed without any knowledge of previous pages requested. This is one of the chief drawbacks to the HTTP protocol. Because maintaining state is extremely useful, programmers have developed a number of techniques to add state to the World Wide Web, including server APIs and the use of cookies.


A contiguous sequence of symbols or values, such as a character string (a sequence of characters) or a binary digit string (a sequence of binary values).

Sun StorageTek 5800 system cluster

Refers to the 16 nodes of the Sun StorageTek 5800 system.


Sun StorageTek 5800 system or Silo

Consists of a half-cell of 8 nodes or a full cell of 16 nodes.

system metadata

Metadata that includes a unique identifier for each stored object, called the OID, as well as information on creation time (ctime), data length, and data hash. It is automatically maintained by the system.

user metadata

Metadata that is added by the user of the Sun StorageTek 5800 system. User metadata consists of name=value pairs. The name is defined in the system schema as of a certain type (for example, a string), and the value is associated with the name at the time data is stored.


Coordinated Universal Time. A time scale that couples Greenwich Mean Time, which is based solely on the Earth's inconsistent rotation rate, with highly accurate atomic time. When atomic time and Earth time approach a one second difference, a leap second is calculated into UTC.


Virtual IP address. The Sun StorageTek 5800 system cluster has two public host addresses, one for the data VIP and one for the administrative VIP.

virtual views

Queries against metadata that are expressed externally as file system paths and file names. A virtual file system view is defined using the metadata attributes defined in the schema.


Web-based Distributed Authoring and Versioning. A set of extensions to the HTTP protocol that provides a network protocol for creating interoperable, collaborative applications.


XML offers a widely adopted standard way of representing text and data in a format that can be processed with relatively little human intervention and exchanged across diverse hardware, operating systems and applications.