The output files from DELANA is automatically written to a local VSAT disk. Even though the VSAT disk capacity has been heavily increased during 97 and 98, these files still need to be processed and thrown away rather fast in order not to fill up our available disk space. The second stage in the VSAT software line is called Compact and it takes all the DELANA output files(one per DELPHI cassette) for one fill and compresses them to a single ZEBRA [7] structure file. ZEBRA is a data format commonly used within the DELPHI collaboration.
Compact also copies the summary information from each DELANA file and creates a summary ntuple file for each fill. The ZEBRA file contains all the event information and the compression from the DELANA output is about a factor 3-4. With the amount of data received for 1998 and onwards even this compressed data set present problems of disk space, since we want to keep all data available on disk. Therefore more disks were bought and at present we have 17 Giga byte of disk space available for data processing.
Managing the data and making quality checks on it is a full time job, and as VSAT staff is steadily decreasing a software package to deal with the most common tasks has been created. This package goes under the name THOR(Total Handling of Offline Re-processing) [8] and should be running constantly on the VSAT data processing station during data taking. This program manages several things: running of Compact, backing up and restoring data, producing quality checking plots and final physics output(see VSDIAG in next section).
The program interacts with mails to the VSAT 'shifter', giving information of what to do or to check. The 'shifter' is the person at CERN taking care of VSAT, normally the shift is about two year long. The program is guided by removing or adding certain files in the program directory. This scheme was implemented to make as little intervention as possible(FTP access) for normal running, but still providing the possibility for total control of the data flow and processing for exceptional cases.