Netbackup catalog backup very long

Hello,

our NBU catalog backup is very long today (it started at 10am, now around 1pm -> 3 hours long, backup uses to last around 2 minutes other days)

The parent job said "begin Catalog Backup, DBM Query" at 11:38 (that's the last log from this job)

An active child job last said "done staging NBDB backup to <install_path>\NetbackupDB\staging at 11:38

A second child job is queued

At this time, the staging directory is still filled up with .db, .conf and .log files

There is a lock on vxdbms_conf file in data directory

There is enough space to backup the catalog (22GB free of 29.9GB)

The server.log file last said "Finished checkpoint of NBAZDB" at 1:38 pm (every 20 minutes)

There is one data restore running at the same time, but it should not prevent the catalog backup to run correctly

Our Master Server is Windows 2008 R2 SP1, NBU version 7.5.0.6

Windows system log don't show anything that could explain while catalog backing is so long today

Do you have any idea ?

Thank you