Replication; Deletion - Dell DX6000 Application Manual

16.4.1. Replication

The ReplicationConstraintSpecialist maintains the desired level of redundancy of
content objects, as well as making sure they are being stored in the most efficient manner possible.
ReplicationConstraintSpecialist understands one constraint name: reps, which can be
set to any integer value.
ReplicationConstraintSpecialist does this by making sure that, at all times, the actual
number of replicas for an object is equal to reps. If a replication constraint is missing from the
lifepoint, a default value is supplied from the node or cluster configuration parameters.
However, the cluster administrator can place additional limits on the number of replicas that can be
specified by defining minreps and/or maxreps in the node or cluster configuration file. If invalid or
conflicting values of the reps constraint are found in a lifepoint, they are ignored, defaults are used,
and warnings are written to the log.
Note
If there is one replica of an object in a cluster, then there is one instance of that object.
Replica, instance and object are all synonymous in this usage. It would also be correct to
say that there is one instance of the object in the cluster.

16.4.2. Deletion

The DeletionConstraintSpecialist completely removes a content object at a certain point
in time, and allows or disallows client applications to delete the content object using the SCSP
DELETE request.
DeletionConstraintSpecialist understands two constraint names: deletable and delete.
Constraint name
deletable
delete
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Description
Can be set to yes|true or no|false.
• yes|true (default) means that normally an object is deletable by any
client that knows its name or UUID. The DELETE method must also be
included in the Allow header for a client delete to be allowed.
• no|false prevents any agent outside of DX Storage from deleting the
object during the effective period of the lifepoint. Any attempt to delete
the object result in a 403 (Forbidden) response.
Does not accept a value.
Causes DeletionConstraintSpecialist to delete the content
object from the cluster. The result is the same as if a client application
had deleted the object.
To avoid ambiguity, when delete is present in a lifepoint specification, it
must be the only constraint in that lifepoint because other conditions on a
deleted object are likely not applicable. Furthermore, a delete lifepoint
must be specified with an empty end date as shown in the following
example.
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Version 5.0
December 2010