3.3

4 Database Management
48
Monitoring Free Space
The iNEWS newsroom computer system is constantly collecting wire stories and adding
them to the database while the news staff adds scripts, rundowns, memos, assignment sheets,
and other stories. To avoid running out of disk space, iNEWS tracks old stories. As stories
get old, the system purges them.
Distribution and purging of disk space is called the database cycle. In this cycle, wire stories
are collected and stored in the database for a specific interval of time. Other news items,
such as scripts and assignment sheets, are created by the news staff and also kept for a preset
period of time, called the purge interval, which is set individually for each queue. Any story
older than its queue’s purge interval is purged, and its space is reclaimed for new stories.
The purge interval is a database trait, so you can set different purge intervals for queues and
directories, depending on the information they hold. Setting purge intervals appropriate for
stories in various queues helps keep the database from growing too large.
Once an hour, at 15 minutes after the hour, an automatic dbpurge program scans each queue
for stories older than the queue’s purge interval and moves these stories into the Dead queue.
Stories sent to the Dead queue are not erased until the system needs the space. Until the
system reclaims this space, stories in the Dead queue can be read, searched, edited, copied,
or printed. To retrieve a story from the Dead queue, select the story and copy it to a different
queue in the database, where you have write permission.
Although you can open stories in the Dead queue, they are marked for removal and will be
permanently removed when the system detects the computer is running out of storage space.
Your system keeps track of the space available by examining and maintaining a list of free
space on the disk. The free list is explained in “Monitoring the Free List” on page 49.
Understanding Database Storage Units
Your computer’s disk is divided into blocks. The database portion of the disk is divided into
1024-byte blocks. When a story is saved, the system allocates as many blocks as necessary
to hold the story and then divides the story among those blocks.
Blocks used to hold a story need not be sequential; a story can be saved in blocks that are
apart. To tie together all blocks, each block contains a reference to the block containing the
next part of the story.
A block is either “in use” or “free”.