Oracle DB backup. A big pause before the start of the backup

Hello Networker 18.2, NMDA 9.2, Oracle 11g After the start of the task on the Oracle DB backup, the size of the database is 10 MB, 20 minutes of pause, and then the backup is performed quickly. What is the reason for the big pause? run { ALLOCATE CHANNEL SBT_CH01 TYPE 'SBT_TAPE' parms 'BLKSIZE=1048576,ENV=(NSR_SERVER=srv-bknw01.x.x,NSR_CLIENT=srv-gisdb01-tst.x.x)'; ALLOCATE CHANNEL SBT_CH02 TYPE 'SBT_TAPE' parms 'BLKSIZE=1048576,ENV=(NSR_SERVER=srv-bknw01.x.x,NSR_CLIENT=srv-gisdb01-tst.x.x)'; ALLOCATE CHANNEL SBT_CH03 TYPE 'SBT_TAPE' parms 'BLKSIZE=1048576,ENV=(NSR_SERVER=srv-bknw01.x.x,NSR_CLIENT=srv-gisdb01-tst.x.x)'; ALLOCATE CHANNEL SBT_CH04 TYPE 'SBT_TAPE' parms 'BLKSIZE=1048576,ENV=(NSR_SERVER=srv-bknw01.x.x,NSR_CLIENT=srv-gisdb01-tst..x.x)'; backup full database TAG "FULL_Backup" format 'FULL_%d_%T_%s_%p' filesperset 50; RELEASE CHANNEL SBT_CH01; RELEASE CHANNEL SBT_CH02; RELEASE CHANNEL SBT_CH03; RELEASE CHANNEL SBT_CH04; } Thanks