HP StorageWorks Storage Mirroring Evaluation Guide (T2558-96326, April 2009)

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Replication
Replication is the real-time transmission of file changes. Unlike other related technologies, which are
based on a disk driver or a specific application, the Storage Mirroring replication process operates at
the file system level and is able to track file changes independently from the file’s related application.
In terms of network resources and time, replicating changes is a more efficient method of maintaining
a real-time copy of data than copying an entire file that has changed.
After a source and target have been connected through Storage Mirroring, file system changes from
the user-defined data set are tracked. Storage Mirroring immediately transmits these file changes to
the target server. This real-time replication keeps the data on the target up-to-date with the source
and provides high availability and disaster recovery with minimal data loss.
Unlike mirroring which is complete when all of the files have been transmitted to the target,
replication continuously captures the changes as they are written to the source. Replication keeps the
target up-to-date and synchronized with the source.
Source Target
User or application updates
part of a file
Only the changed
portion of the file is
Up-to-date copy maintained
on the target
replicated