On a side note, does Retrospect check for identical files
between backup clients? I have 30 macs with identical system
folders. I really only need to backup those system files once. If
retrospect was so smart, I could do full backups site wide and get
most efficient coverage with minimal tape space. I note it tends to
backup more than it needs to because of volume name, time stamp, etc.
At 3:49 AM -0700 06/29/00, Ming-Li wrote:
>Hi Matthew,
>
>> Retrospect uses several matching criteria to compare files
>> that have already been backed up to what is about to be backed
>> up. If one of the following has been changed at all,
>> Retrospect will back up the file again:
>>
>> MAC files:
>> name, size, type, creator, creation date and time,
>> modify date and time, and label.
>>
>> PC files:
>> name, size, modify date and time, file system.
>
>Have you ever consider using something even more accurate as the
>criterion--say, CRC32, or some sort of file signature? Will it
>slow down Retrospect significantly than the current approach?
>
>I'm asking because I've found many different applications put
>same version of system files (dll and such) with different
>date/time. The file name, size and version no. (by checking the
>file's properties) stay the same, and a binary comparison would
>show the two files are identical. They have touched the
>date/time probably because they want all their files to have the
>same date/time, or because the original software development
>package (MS C++, Delphi, etc.) did so. And some other software
>would make the date/time of its installation the date/time of
>all the files it put in, regardless their original date/time.
>
>Under current design, Retrospect would back those files up
>again. By way of CRC32 check, Retrospect would find those files
>are indeed identical to the original ones and skip them. It
>would not only save storage space, but also give me extra
>confidence for whenever I catch some new application overwriting
>my system files, I can look in Retrospect's backup preview
>window and find which of them are in fact identical (hence no
>worry) and which are different (so I might have to restore my
>backed up version to see which one is in fact newer).
>
>I don't know if any application would change a file's content
>without changing its date/time and size. But if that happens, a
>CRC32 check would expose them, too.
>
>--
>Best regards,
>Ming-Li
>
>
>
>
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