5.6 HP StorageWorks X9000 File Serving Software User Guide (TA768-96035, June 2011)

11 Using remote replication
This chapter describes how to configure and manage remote replication.
Overview
Remote replication provides a transparent method to replicate changes in a source file system on
one cluster to a target file system on either the same cluster or a second cluster. The remote
replication service has two modes: continuous and run-once.
Both files and directories can be replicated with remote replication, and no special configuration
of segments is needed. A remote replication task includes the initial synchronization of the source
and target file systems.
When selecting file systems for remote replication, you should be aware of the following:
• One, multiple, or all file systems in a single cluster can be replicated.
• Remote replication is a one-way process. Bidirectional replication of a single file system is not
supported.
• The mountpoint of the source file system can be different from the mountpoint on the target
file system.
Remote replication has minimal impact on normal cluster operations:
• Cluster expansion (adding a new server) is allowed as usual on both the source and target.
• File systems can be exported over NFS, CIFS, FTP, or HTTP.
• Source or target file systems can be rebalanced while a remote replication job is in progress.
• File system policies (ibrix_fs_tune) can be set on both the source and target without any
restrictions.
The management console initializes remote replication. However, each file serving node runs its
own replication and synchronization processes, independent of and in parallel with other file
serving nodes. The ibrcfrd daemons running on the file serving nodes perform the actual file
system replication.
The source-side management console monitors the replication and watches for errors, failures, and
so on.
Continuous or run-once replication modes
Remote replication can be used in two modes: continuous or run-once.
Continuous remote replication. This method tracks changes on the source file system and continuously
replicates these changes to the target file system. The changes are tracked for the entire file system
and are replicated in parallel by each file serving node. There is no strict order to replication at
either the file-system or segment level. The continuous remote replication program tries to replicate
on a first-in, first-out basis.
When you configure continuous remote replication, you must specify a file system as the source.
You can specify either a file system or a file system and directory as the target. The following
requirements apply:
• File systems specified as the replication source or target must exist.
• If a directory is specified as the replication target, the directory must exist on the target.
Run-once remote replication. This method allows for replication of a single directory sub-tree or an
entire file system from the source file system to the target file system. Run-once is a point-in-time
replication of all files and subdirectories within the specified directory or file system. All changes
Overview 87