[Dirvish] move/rename files/folders

Eric Wilhelm scratchcomputing at gmail.com
Thu Jun 21 17:13:35 UTC 2007

# from Marco Jackel
# on Thursday 21 June 2007 01:43 am:

>what happen if I move or rename files or folders in a directory that
>gets backuped every night. Are those "new" files/folders hardlinked to
>the existing ones in the backup, too?

No.  The backup linkage is by-name only.

There are backup systems that do checksum-based pooling[1], which allows 
sharing the space used for identical files even if they came from 
multiple source machines, but dirvish is not one of those.

[1] The files are stored in a single repository named by an md5sum 
fingerprint of their contents and trees are replicated by hardlinking 
the names to the content files.  This saves space at the expense of 
cpu/disk load depending on your situation.  Some schemes might use 
size/dates as a first-check to avoid recreating checksums iff the files 
did not get renamed.  Similarly, multiple same-distro source machines 
might be able to avoid transferring files such as /usr/lib/libc.so but 
they'll still have to initially do the checksum somewhere.

"It ain't those parts of the Bible that I can't understand that
bother me, it's the parts that I do understand."
--Mark Twain

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