Term	Definition
extents	Objects are stored on the disk in one or more extents, which can be files in the file system, data in raw partitions, or a mixture. An extent is divided up into a number of pages and disk i/o is performed in units of a page.
gcgem	A specialized gem that performs garbage collection tasks.
GCI	GemBuilder for C Interface. The GCI library is used for communication between client Smalltalk images and gems.
gem	A GemStone VM.
netldi	The GemStone network server process is called NetLDI (Network Long Distance Information). Each NetLDI reports the location of GemStone services on its node to remote processes that must connect to those services. It also spawns other GemStone processes on request.
Object Table	A Btree-based data structures that maintains a mapping between the OOP of an object and the page that the object is located on.
OOP	A unique object id.
page	A page is approximately 16K bytes. Pages are loaded directly into the Shared Page Cache, providing access to objects, and other system data structures.
pagemanager	A process that coordinates the management of pages on the Stone’s Shared Page Cache as well as remote Shared Page Caches.
pgsvrmain	A process that is attached to the Shared Page Cache that performs one of a number of maintenance tasks: free frame management (Free Frame Page Servers), page management (AIO Page Servers), and local communication on behalf of remote gems.
Repository	The GemStone database.
Session	A Session is created when a User is authenticated in a gem process. All GemStone activity is carried out in the context of a Session. Not to be confused with a web session (WASession).
Shared Page Cache	A segment of the operating system’s virtual memory where objects are cached and are accessible to all gems running as Sessions in the same Stone.
shrpcmonitor	A process that creates and maintains a shared page cache for the GemStone server. The size of the shared page cache is configurable and should be scaled to match the size of the repository and the number of concurrent sessions.
Stone	The collection of processes (gem, pgsvrmain, stoned, shrpcMonitor, topaz), Extents, Transaction Logs and Shared Page Cache that work together to serve up the objects stored in the extents.
stoned	A process that acts as a resource coordinator. It synchronizes critical repository activities and ensures repository consistency.
transaction logs	Transaction logs permit recovery of committed data if a system crash occurs. They also reduce disk activity by eliminating the need to flush to the extents all data pages written by each transaction.
topaz	A program that provides command line access to GemStone. Allows one to build Smalltalk scripts that get executed by a gem
User	A GemStone User has an ID, password, priviliges for executing certain functionality (i.e., Garbage Collection, or Code Modification), and permissions for accessing objects in the Repository. Not to be confused with the web user associated with a web session.