Archiving and backup (DiskXtender)

A lot of my customer cannot distinguish between archiving and backup. They think archiving is the same as backup as well as safe them space on primary storage. This is wrong. Archiving is a process of moving inactive or infrequently accessed data from primary storage to other cheaper storage. For example, moving from a lun of Symmetrix to Centera. If settings in Centera are correct, it can reduce duplication of data being saved on the target.

Backup will save a secondary copy of information. Archive only moves the data to another storage media. You still have only one copy of the data. Use EMC DiskXtender as an example, if files are moved to secondary media and rules are setup properly, files that were moved to secondary storage can now be purged from the primary storage and leave a shortcut on the primary storage. The shortcut contains info about the location of the file in the secondary storage. When you click on it, the program will fetch the file back from secondary storage. You can also apply retention on the files if using NetApp / Centera. This can prevent files from being modified. If a moved file / shorcut (already moved to secondary storage) with no retention is deleted from primary storage, it will be deleted from the secondary stoarge too.

DiskXtender relies on extended attribute to locate the file in the secondary storage. Make sure the backup solution is full NTFS aware or you will regret! Besides, never try to overwrite existing shortcut / moved files on the primary storage by restoring from backup. This can cause the file in the secondary storage being overwritten by zero kb file. What that means ...... Data Loss! Please check all the guides before deploying the solution. Besides, archiving solution is for inactive or infrequently accessed files. If you plan to use it for frequently modified file, you should increase in primary storage space instead. Again, this is not a replacement for your backup software.