Tandberg Data NAS Hardware Viking FS-1500 - Manual (Page 95)

Tandberg Data Distributed File System
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7-5 Tandberg Viking Series Storage Server Administration Manual
7.3.2. DFS Initial Replication
When you first set up replication, you must choose a primary member.
Choose the member that has the most up-to-date files that you want
replicated to all other members of the replication group, because the primary
member's content is considered "authoritative." This means that during initial
replication, the primary member's files will always win the conflict resolution
that occurs when the receiving members have files that are older or newer
than the same files on the primary member.
The following explanations will help you better understand the initial
replication process:
• Initial replication does not begin immediately. The topology and DFS
Replication settings must be replicated to all domain controllers, and
each member in the replication group must poll its closest domain
controller to obtain these settings. The amount of time this takes
depends on Active Directory replication latency and the long polling
interval (60 minutes) on each member.
• Initial replication always occurs between the primary member and
the receiving replication partners of the primary member. After a
member has received all files from the primary member, then that
member will replicate files to its receiving partners as well. In this
way, replication for a new replicated folder starts from the primary
member and then progresses out to the other members of the
replication group.
• When receiving files from the primary member during initial
replication, the receiving members that contain files that are not
present on the primary member move those files to their respective
DfsrPrivate\PreExisting folder. If a file is identical to a file on the
primary member, the file is not replicated. If the version of a file on
the receiving member is different from the primary member’s
version, the receiving member's version is moved to the Conflict and
Deleted folder and remote differential compression (RDC) can be
used to download only the changed blocks.
• To determine whether files are identical on the primary member and
receiving member, DFS Replication compares the files using a hash
algorithm. If the files are identical, only minimal metadata is
transferred.
• After the initialization of the replicated folder, the "primary member"
designation is removed. Initialization takes place after all files that
exist before DFS Replication picks up the configuration are added to
the DFS Replication database. The member that was previously the
primary member is then treated like any other member and its files
are no longer considered authoritative over those of other members
that have completed initial replication. Any member that has
completed initial replication is considered authoritative over
members that have not completed initial replication.