Unix Tip: WHY MV IS SLOW

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UNIX HOT TIP

Unix Tip 2454 - September 20, 2005

http://www.ugu.com/sui/ugu/show?tip.today

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WHY MV IS SLOW

mv command across filesystems is slower on large files

WHY?

mv would be slow if you are moving files across filesystem.

The inode number changes only when a file is moved across file system.

A new inode number means a new file is physically created on disk.

It remains unchanged, if it is within the same filesystem. One can verify by using ls -il command on that file.

mv uses rename() system call. if it fails, it uses copy routine (basicailly reads from a file and writes in another file).

mv command across filesystem is more of a copy then mv.

This tip generously supported by: dkotian1@rediffmail.com

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