Interviewer: Lets say there is a partition of 100GB. When i tried to create a

Interviewer: Lets say there is a partition of 100GB. When i
tried to create a file using touch command, under any
directory, it was unable to create the file- '100% full
disk space'. I calculated the size of each and every
directory on that partition mannually by adding each file
size & in came out to be total size 50GB. Then where is the
remaining 50GB ? why it is showing disk space 100% full
in 'df -h' command?

Question Posted / pal

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Interviewer: Lets say there is a partition of 100GB. When i tried to create a file using touch com..

Answer / kenji

One possibility is that there are many small size files. "Small" is relative to block size. For example the block size of ext3 file system is 4096. A file size of 4097 uses 2 blocks resulting 50% efficiency. This can explain why 100G partition gets disk full at 50G usage.

Another possibility is there are processes having large open files which are not linked. Such files are not visible by 'ls' commands but their usage still shows up by df -h.

At the event of 'disk full' I would check inode usage as well. Normally max inodes were allocated as "partition size / block size" so insufficient inodes rarely happens. typing 'df -i' doesn't cost you much :-)
I initially thought of "inode full" which you can check by df -i

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Interviewer: Lets say there is a partition of 100GB. When i tried to create a file using touch com..

Answer / kenji

I guess "inode checking" part I posted was extraneous and not really true for today's large disk.

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