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Title
Large lastlog or sparse file size. How to set maximum UID allowed. -
Description
Large /var/log/lastlog file also know as the sparse file size or How to set maximum UID generated allowed. -
Cause
/var/log/lastlog also known as the sparse file gets written to when you log in. The size of this file is based off of the largest UID in the system. The larger the maximum UID, the larger this file is.UID Maxium is 2101682400. Each ID on the server gets one 256 Bytes record allocated on server in /var/log/lastlog file,That file called "sparse" file. Operating system has to create 2101682400 user records in "lastlog" file:2101682400 * 256 / 1034 / 1024 / 1024 = 496 GBResulting in sparse file size 496 GB. However, since lastlog is a sparse file, its reported file size isn't always the size it consumes on the UNIX file system. The man page for lastlog explains the confusion. -
Resolution
WORKAROUND 1:You can set the Maximuim UID in the control center.1- Go to the QAS Control Center2- Click on Preferences on the left panel3 - Select Modify Global Unix Options ... (blue link in pane on right hand side)4- Enter in a Maximum UID number that is smaller to get a smaller sparse file.Please note: The control center (CC) min and max settings do not have any affect on GID and UID generated when using the autogen-posix-attrs true setting. The generation of IDs with this setting are explicitly based off the GUID.