NAME

NSR crash − How to recover from a disaster with NetWorker

DESCRIPTION

NetWorker can be used to recover from all types of system and hardware failure that result in loss of files. 

When a NetWorker client has lost files, the recover command can be used to browse, select, and recover individual files, selected directories, or whole filesystems.  If the networker recover command is lost or damaged it will have to be copied either from another NetWorker client or from the NetWorker distribution tape. 

When recovering a large number of files onto a filesystem that was only partially damaged, you may not want to overwrite existing versions of files.  To do this, wait until recover asks for user input to decide how to handle recovering an existing file.  You can then answer N meaning “always no” to cause recover to avoid overwriting any existing files, or n if you want to protect this file but you want recover to ask again on other files. 

If you do want to replace the existing version of a file or set of files with the saved versions use the add command in recover to select which files should be retrieved, and answer Y or y when it asks if it should overwrite existing files (Y means “always yes” for future overwrite cases; y means just overwrite this one file). 

For more information on using the recover command see the recover(8) manual page. 

If the NetWorker server daemons or commands are lost, it may be necessary to re-install the server from the NetWorker distribution tape.  Once the NetWorker server is installed and the daemons are running, other NetWorker server files can be recovered using the recover command.  When re-installing NetWorker you must be sure to install the /nsr directory in exactly the same place as it was originally installed.  The machine used to recover files may be different that the one used to save the files, but it must have the same hostname as the original machine.  This is important because recovery of the NetWorker on-line index requires that the index files have the same pathname, which includes the server’s hostname, as they did at the time of the latest save. 

In the event that the NetWorker server’s index is lost, it will be necessary to first recover the index from media before the recover command can be used to browse and recover other files.  To recover the NetWorker server’s index use the recoverindex command.  The recoverindex command quickly recovers the lost on-line index for a NetWorker server by locating the bootstrap save set produced by the savegroup(8) command at the end of an automatic save.  The bootstrap save set tells recoverindex which save sets to extract from which volumes to recover the whole index.  The save set identifier and other information about the bootstrap save set is printed by savegroup at the end of each automatic save.  See the saveindex(8) and savegroup(8) manual pages for more details. 

After recoverindex completes, the server’s file index and media database will be fully recovered (unless recoverindex prints an error message to the contrary).  However, the NetWorker server’s /nsr/res directory, which contains the resource files describing your NetWorker installation, require additional work on the part of the administrator before they will be used.  Perform the following steps to complete the recoverindex process (these steps will be incorporated into recoverindex in a future release). 

1.Shut down your NetWorker server (nsr_shutdown -a). 

2.Change to the /nsr directory (cd /nsr). 

3.Save the temporary resource directory created by nsr_ize (mv res res.save). 

4.Move the recovered resource directory into place (mv res.R res). 

5.Restart the NetWorker server (cd / ; nsrd). 

6.After verifying that the recovered resources are valid, remove the temporary resource directory (rm -r /nsr/res.save). 

NOTE: The recoverindex command is only used to recover the NetWorker server’s index.  Use recover to recover a client’s index. 

Once recoverindex is run and the media database has been recovered, one can use the recover by save set feature to restore entire filesystems.  This method can be faster as one does not have to use a browser to mark all the files and directories in a file system, an operation which can take a long time.  You should only use this method for recovery of a filesystem when you can locate a recent save set for that filesystem which was saved with level=full.  When recovering multiple save sets which are interleaved on media, recover will recover all save sets concurrently instead of making a separate pass over the media for each save set.  See the recover(8) man page for details on running recover by save set. 

If you want to recover whole filesystems, an alternative to using recoverindex and recover is to use the scanner command to recover all of the files in a particular save set.  The scanner command can also be used to print a table of contents for a volume to help you locate the correct save set for a filesystem.  Similar to recover by save set, you should only use scanner for recovery of a filesystem when you can locate a recent save set for that filesystem which was saved with level=full.  If using this method of recovery, use of the −x option is preferred to simply piping the output through uasm as multiple save sets interleaved on the media can be read concurrently instead of making a separate pass over the media for each save set.  For example, the first command is preferred to the second:

scanner -s 16234 -s 16257 -x’uasm -r’
scanner -s 16234 -s 16257 | uasm -r

See the scanner(8) manual page for more details. 

If the server is damaged so badly that it will not run at all, you will need to follow the manufacturer’s instructions for re-installing and rebooting a multiuser system.  Once you have the system up and running in multiuser mode, you can re-install NetWorker (i.e. extract NetWorker from the distribution tape and install it, using nsr_ize(8)) and use recoverindex to rebuild the on-line index.  Finally, you will want to recover files which previously existed on the machine, but which do not exist on the manufacturer’s distribution tape.  This may include: system files which had been customized, a specially tailored kernel, new special device entries, locally developed software, and user’s personal files. 

SEE ALSO

nsr_ize(8), nsr_layout(5), nsr(8), recover(8), savegroup(8), saveindex(8), scanner(8). 

NetWorker 4.1.2  —  Last change: May 1995