OSF DCE Administration Guide--Core Components

OSF DCE Administration Guide—Core Components
during an update propagation and to remove outdated information from the namespace.
For hierarchical cells, the skulk updates the child pointers in the parent cell and the up
pointers in the child cell (which point to the parent) so they reflect the updated
information.
Skulk maintenance functions include the following:
• Removing soft links that have expired. You can specify an expiration time when you
create a soft link.
• Maintaining child pointers, which includes removing pointers to directories that were
deleted.
• Removing information about deleted replicas.
CDS skulks each directory individually. During a skulk, CDS collects all changes that
were made to the master replica since the last successful skulk and then disseminates the
changes to all read-only replicas of the directory. All replicas must be available for a
skulk to be considered successful. If CDS cannot contact a replica, it continues making
changes in the replicas that it can contact, while generating an event to notify you of the
replica or replicas it could not update. CDS then periodically reattempts the skulk until it
completes successfully.
A skulk can begin in one of three ways:
• A CDS manager can enter a command to start an immediate skulk on a directory.
• CDS starts a skulk as an indirect result of other namespace management activities,
which include the following:
— Adding or removing a replica
— Creating or deleting a directory
— Redesigning replica types
— Adding or deleting a child cell name in a parent cell
All of these activities produce changes in the structure of the namespace, so an
immediate skulk ensures that the new structure is reflected throughout the namespace
as quickly as possible.
• The CDS server initiates skulks automatically at a routine interval called the
background skulk time.
The background skulk time interval guarantees a maximum lapse of time between
skulks of a directory, regardless of other factors, such as namespace management
activities and user-initiated skulks. A CDS server periodically checks each master
replica in its clearinghouse and initiates a skulk if changes were made in a directory
since the last successful skulk of that directory.
14.3 How Timestamps Help Keep Data Consistent
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