Backup / Restore of UNIX File Systems

If you have UNIX servers on your network, install a Linux DS-Client to perform backup / restore.

This article deals with issues for the backup set kind “NAS, UNIX-SSH, NFS, Local File System Backup“ from a Linux DS-Client.

When backing up any target UNIX machine (Local File System, via UNIX-SSH or NFS), the following directories are always excluded from backup (even if selected in a backup set):

These directories constitute pseudo-file system(s), which do not contain physical files or do not contain persistent data.

If excluded directories are skipped during a backup, a warning appears in the Event Log for that activity.

In addition to the above general UNIX directory exclusions, the following directories are excluded from UNIX-SSH backup sets of SOLARIS machines:

NOTE: The zoneFS path can be shown with the “zoneadm list” function.

Hard Links are created in Unix-based file systems with the ‘ln’ function. In general, if you want to perform backup and restore of hard links, you must create a backup set that includes all files that are linked through hard-links.

If even one linked file (from a hard link group) is not included in a backup set, the backup will not be able to record all the hard-link information. Similarly, for a restore, if only some of the hard-linked files are selected for restore, the restore will only link the hard-linked files that are restored.

If it is desired to restore only one file, and preserve any existing hard-links, then use the Fast restore option. Note: this will also change the data of the other linked files not restored.

• By default, the “Backup hard links” option is selected for any new backup sets. This means the backup will record file and hard link information during backup, so that the hard links to be restored.

• If the option Backup hard links is not selected for a backup set, this means any backed up hard link will be backed up and restored as a separate (individual) file. In this case, the backup set will not contain any hard link information.

• Even with the option Backup hard links selected, you must create a backup set that includes all the hard linked files. Otherwise a warning will appear in the Event Log for the backup activity and if you restore from that backup, your existing hard links will be broken. The same applies if you perform a partial restore of hard linked files.

Restoring hard links assumes the backup contains all hard linked files and file information. (For example: If the source computer has 5 files that are hard linked, your backup set must contain those same 5 files and the backup set must have the “Backup hard links” option selected.)

The restore behavior for hard linked files depends on the “Restore Method” selected in the Restore Wizard’s “Select restore options” screen:

• Save / Use Buffer: This is the default restore method, which will restore the selected hard linked file(s) and recreate the hard links for those restored files.

• Fast: This method allows you to selectively restore the hard link data (inode information) from a single file while preserving the existing hard link information on the restore target. After restore, this effectively changes the data of the other linked files (that were not restored).