No matter who offers the service, the result is the same: Data is moved offsite and protected from any local geographical disaster. Examples of products in this category include the following:
– CrashPlan for Business: Code 42 Software
– Zettabits Storage System: Zettabyte Storage
Other companies have announced intentions to enter this market, but at the time of this writing, have no released products. This is a backup category to track closely.
Backing Up LAN-Free
LAN-Free Backup is a relatively new scheme, available only when a Fibre Channel SAN is in place. As the name suggests, in a LAN-Free backup, no data travels over the LAN. A backup server on the SAN has access to a directly attached storage unit or Fibre Channel tape unit in a switch. All data to be backed up is written to a volume or volumes on the SAN. From there, the backup can be picked up by the SAN-bound backup server.
Comparing Backup Methods
All backup methods seek to match the appropriate data with appropriate storage. Not all data needs to be backed up using the same method. For all backup methods, you also need to consider restoring and restore speed. You must routinely perform restore testing. All backup methods also must take into account the unique attributes of the Mac OS X HFS+ file system.
Current versions of HFS+ can store access control lists (ACLs) for file system objects, along with metadata and general extended attributes, and forked files. (Forked files, a file type unique to the Mac OS, have a data fork and resource fork.) All of this metadata needs to be kept intact with its associated files. It’s important that backup software for Mac OS X systems protects this information on backup and can also put it back properly on restore.
An excellent test suite is Backup Bouncer by Nathanial Grey (http://www.n8gray.org/ blog/2007/04/27/introducing-backup-bouncer/). Backup Bouncer takes a source directory that is filled with files that have resource forks, extended attributes (EAs), and ACLs applied. You back this up with the software you’re testing, and restore it elsewhere. Backup Bouncer then reports on how well the backup software performed in retaining various categories of file system attributes. These file system attributes go beyond pure data; many are unique to the Macintosh platform and Mac OS X. It’s important that a backup solution account for them. Some Mac OS X native solutions treat these attributes properly, but not all do.
Non-native Mac OS X solutions, where Mac OS X is one of many client types able to be backed up, are typically even less capable of handling attributes properly. However, retaining these categories of attributes is critical for the file system, the proper functioning of services that rely on this metadata, and the OS itself.