HP StorageWorks Storage Mirroring for Linux User's Guide (T2558-96078, February 2008)
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5 X Replication Sets
Replication Sets
A replication set defines the data on a source machine that is to be protected by Storage Mirroring. Replication sets are
defined by the volumes, directories, files, or wild card combinations that are to be replicated to the target. Creating multiple
replication sets allows you to customize sets of data that need to be protected.
Replication Set Rules
Replication sets are created by defining rules. Each replication set rule consists of:
Path—The path including volume, drive, directory, file, and/or wild card
Include—If the path and/or file is to be included in the files sent to the target
Exclude—If the path and/or file is not to be included in the files sent to the target
Recursive—If the path should automatically be applied to the subdirectories of the named directory
For example, a replication set rule might be
volume/directory/* inc, rec
This specifies that all files contained in the volume and directory path are included in the replication set. Because recursion is
set, all files and subdirectories under volume\directory are also included. The replication set becomes a list of replication set
rules. For example, suppose you want to protect your network server which contains an important customer database. You
might create a replication set with the following rule.
/customer/*.db inc, rec
This rule includes all database files from the customer directory. Recursion is specified with this rule so all .db files in any
subdirectory under that directory will also be included in the replication set.
Replication Capabilities
Storage Mirroring replicates all file and directory data stored on any Linux file system (ext2 and ext3). It does not replicate
items that are not stored on the file system, such as pseudo-file systems like /proc and /sys. In addition, note the following.
Data that will be replicated must reside on a Storage Mirroring partition, which is specially mounted with the Storage
Mirroring file system (DTFS) driver. DTFS is a virtual file system that monitors the storage file system so that data changes
can be captured. DTFS is a transparent file system. Existing mount points may be available for replication, but the data on
those mount point can only be replicated if they are DTFS mount points. The DTSetup utility allows you to specify which
mount points should be DTFS mount points. See the Getting Started guide for more information on the DTSetup utility.
DTFS mount points are identified in the Management Console by dtfs in the mount point name.
Storage Mirroring is compatible with NFS and Samba as long as they are mounted on top of Storage Mirroring. Storage
Mirroring should be mounted just above the storage file system.
Do not select the root as a replication mount point.
If you have a single drive system, mount DTFS to any of the subdirectories directly under root that you want to replicate.
If you select data stored on a recursive mount point for replication, a mirror will never finish. Storage Mirroring does
not check for data stored on recursive mount points.
If any directory or file contained in your replication set specifically denies permission to the account running the Storage
Mirroring daemon, the attributes of the file on the target will not be updated because of the lack of access.
If you are using soft links, keep in mind the following.
NOTE: Rules can be written for paths that do not currently exist. To enter a nonexistent path, you will have to
manually enter the rule.
NOTE: Replication set rules are limited in length meaning that the entire volume, directory, and filename including
slashes, spaces, periods, extensions, cannot exceed 259 characters.
Storage Mirroring can mirror, replicate, verify, and restore file names up to 32,760 characters, although each
individual component (file or directory name) is limited to 259 characters. File names longer than 32,760
characters (due to the concatenation of the source and target paths) will be skipped and logged to the Storage
Mirroring log file and the Linux system log.