HP StorageWorks Storage Mirroring for Linux User's Guide (T2558-96317, June 2009)

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Replication Sets
A replication set defines the data on a source machine that Storage
Mirroring protects. Replication sets are defined by volumes,
directories, files, or wild card combinations. Creating multiple
replication sets allows you to customize sets of data that need to be
protected.
When a replication set is created, a series of rules are defined that identify the volumes, directories,
files, and/or wild card combinations that will be replicated to the target. Each rule includes:
 Path—The path including volume, drive, directory, file, and/or wild card
 Include—If the specified path is to be included in the files sent to the target
 Exclude—If the specified path is not to be included in the files sent to the target
 Recursive—If the rule should automatically be applied to the subdirectories of the specified path
For example, a replication set rule might be
volume\directory\* inc, rec
This specifies that all files contained in the volume\directory path are included in the replication set.
Because recursion is set, all files and subdirectories under volume\directory are also included. A
complete replication set becomes a list of replication set rules.
Replication sets offer flexibility tailoring Storage Mirroring to your environment. For example, multiple
replication sets can be created and saved for a source to define a unique network configuration. There
may be three replication sets - Critical Data, User Data, and Offsite Data. Critical Data could be
configured to replicate, in real-time, to an onsite high-availability server. Offsite Data is replicated
across a WAN and, therefore, is configured to queue changes until a sufficient amount of data is
changed to justify transmission. At that point, the connection is made and stays active until all the
data is transmitted. User Data is not replicated throughout the day, but a nightly changed file mirror
copies only blocks of data that are different between the source and target server prior to a nightly
tape backup operation being run on the target server. Each of these replication sets can be automated
to transmit as needed, thus protecting your entire environment.
Keep in mind the following notes when creating and working with replication sets and connections.
 Limitations
 Replication set rules are limited in length meaning that the entire volume\directory\filename
including slashes, spaces, periods, extensions, cannot exceed 259 characters.
 Storage Mirroring can mirror, replicate, verify, and restore paths up to 4,095 characters. Paths
longer than 4,095 characters will be skipped and logged to the Storage Mirroring log file and
the Linux system log.
 Do not name replication sets or select a target location using illegal characters. Illegal
characters include the following.
 Error checking and avoidance
 Do not connect more than one replication set to the same location on a target. You could
overwrite or corrupt your data.
 Replication sets contain error checking to avoid inadvertent overwrites of the replication set
rules. When replication sets are modified, a generation number is associated with the
modifications. The generation number is incremented anytime the modifications are saved,
but the save is not allowed if there is a mismatch between the generation number on the
source and the Management Console. You will be notified that the replication set could not be
saved. This error checking safeguards the replication set data in the event that more than one
client machine is accessing the source’s replication sets.
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