Bug#922945: /var/log/lastlog is a 110 TByte sparse file, seriously affecting backup

[Harald Dunkel]

Package: login
Version: 1:4.4-4.1

Somehow /var/log/lastlog grew to a 110 TByte sparse file:

        # ls -al /var/log/lastlog
        -rw-rw-r-- 1 root utmp 110784817228 Feb 22 08:37 /var/log/lastlog

        # du -h /var/log/lastlog
        88K     /var/log/lastlog

This affects rsync performance seriously, even when -S is used.
To reproduce the problem, please try

        # time rsync -SHa /var/log/lastlog /dev/shm
        
        real    4m0.621s
        user    6m36.402s
        sys     0m58.913s

Using our backup system as a destination for rsync I gave up waiting
after 15 minutes.

Do you think this could be improved?


UID_MAX is 60000, but our user database is freeipa on CentOS 7.6.
This might be related:

        # getent passwd admin
        admin:*:379400000:379400000:Administrator:/home/admin:/bin/bash


Regards
Harri