4. Preparing for analysis
Once you have written your event tapes you should verify that the data on them is a faithful copy of the original data on disk. To do this, you should get an analysis area, and use it to recover both the event data tapes and the experiment home directory tree. How you do this will depend on whether you are analyzing your data at the NSCL, or taking it to some other home institution for analysis.
To analyze your data at the NSCL, you should first get an evtdata and a projectarea. The evtdata area is intended for read-mostly access. You will read your stagearea tapes into the evtdata area. The project area will be where you do most of your analysis and where the products of this analysis should be stored. You will restore you home directory tapes into the project area. Normally both the evtdata and projects directory will be created and assigned to you at the same time your experiment account was created.
 | The evtdata area is not backed up by the computer department. any data you want automatically backed up belongs in the project directory, which is backed up by the computer department. |
Table 3. Tape Drives available on tapehost.nscl.msu.edu
| Tape Drive | Drive Type | Capacity | Media |
|---|---|---|---|
| /dev/st0 | DLT IV | 10 - 50 Gbytes | DLT IV |
| /dev/st1 | LTO-2 | 200 Gbytes | LTO-2 |
Suppose you have arranged for space into which recover the data from your experiment. First, login to the system tapehost.nscl.msu.edu as yourself. If the evtdata space is called $MYEVTDATA, and the project directory $MYPROJECT then to restore both the event and home directory data tapes we recommend the following procedure.
bash$ cd $MYPROJECTMount the first home directory tape in the drive and type:
bash$ tar Mxf tapedrivewhere tapedrive is the name of the tapedrive on which you have mounted your event tape. At the NSCL, this drive will be one of the drives on the system tapehost.nscl.msu.edu located at the left side of data-U 2.Change tapes as requested until all of the tapes in your home directory tape set have been read in.
Next set your default directory to your evtdata directory:
bash$ cd $MYEVTDATA
Mount your first event data tape and type:
bash$ tar Mxf tapedriveChange tapes as requested until all of the tapes in your event data set have been read in.