Unneccessary md5sum calls
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#4 Unneccessary md5sum calls
After the last backup run, I discovered that the md5sum
was calculated for almost all files. Some random
samples using ps proved that storebackup calculates the
md5sum of files whose mtime lies far behind the last
backup.
Unfortunetaly, the debug mode didn't tell me why the
md5sum was calculated.
This phenomena enhances the backup time significantly,
because almost all data is read and only a minor
percentage actually written.
How is that to explain and how can I avoid it?
Thanks,
Nikolaus
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user_id=529453
This is not a bug.
storeBackup stores the ctime (creation time), mtime (modify
time) and size of all files of a backup in the .md5CheckSums
File in every backup directory.
When you make a new backup, then it checks, if any of the
values has _changed_ (values of the files to backup vs.
values in the .md5CheckSums file). The ctime or mtime of
the files in the backup does not matter at all.
If at least one of the values has changed, the md5sum is
calculated.
storeBackup does only check if the times a different,
because if your clock is not set up properly, this is the only
save way to recognize a change.