[Bug 1707645] Re: system with high numbered uids has huge sparse /var/log/lastlog

[aaron]

Someone needs to take on all the affected systems, PAM, users etc to
find a fix.

In redhat this has been an open issue since 2013. If anybody sees this
hopefully it will direct interested parties to places where other people
are talking about the same issue.

This also becomes an issue in Docker containers, where user IDs are large. 
Great way to fill up your docker image with junk. 

https://bugzilla.redhat.com/show_bug.cgi?id=951564

** Bug watch added: Red Hat Bugzilla #951564
   https://bugzilla.redhat.com/show_bug.cgi?id=951564

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https://bugs.launchpad.net/bugs/1707645

Title:
  system with high numbered uids has huge sparse /var/log/lastlog

Status in pam package in Ubuntu:
  Confirmed
Status in shadow package in Ubuntu:
  Confirmed
Status in util-linux package in Ubuntu:
  Confirmed

Bug description:
  I was investigating the use of a single high UID user (ie, 2000000000)
  and discovered that /var/log/lastlog grew to an enormously large
  sparse file:

  $ ls -lh /var/log/lastlog 
  -rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

  The file is actually quite small though:
  $ ls -lh --size /var/log/lastlog 
  56K -rw-rw-r-- 1 root utmp 544G Jul 27 12:35 /var/log/lastlog

  On a standalone system, this is possibly not a problem since it is
  highly unlikely that a system will have 2 billion users, but this is
  confirmed to wreak havoc on rsync backups.

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