During backup of a database's data stored in individual files, it is not permissible
for the data in the individual files to be altered, for reasons of consistency.
For this reason, the files are blocked to altering access operations after a particular
time during a backup operation. According to the invention, the backup operation
is carried out in two parts. First, the files are transferred without there being
any alteration block. A recording file is used to note files which are altered
during transferring. These files are transferred again in a second part. During
the second part an alteration block is required. It can be assumed that the number
of files needing to be transferred in the second part is much smaller than the
number of files needing to be transferred in the first part. For this reason, a
significantly shortened alteration block is achieved.