My backup team reported that the backups are failed. And on investigation I found /var/log/lastlog is very huge in size but file system usage is normal in "df" output. And even "du" command also shows normal in size. I found this information from redhat. This file is what we call a sparse file. A sparse file is a file that contains unallocated blocks or "empty space", as it implies, it does not actually take up filesystem space. To test this theory, execute the following command: root@server1.nyc.us:/var/log # ls -l /var/log/lastlog -rw-r--r-- 1 root tty 459561084068 Jul 1 13:05 /var/log/lastlog root@server1.nyc.us:/var/log # du -sh /var/log/lastlog 23M /var/log/lastlog See the ls -l output, which shows huge size. The fix which they have suggested is to copy/move the file to some other place, because the copying will clear the unallocated blocks. But I found the copy is taking more time. So I decided to to clear the file after stopping th...
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