kaikow Posted July 10, 2003 Report Share Posted July 10, 2003 It is my understanding that Retrospect tries to guess whether a file has already been compressed and does not compress a file that appears tro have already been compressed, such as a .zip, or a fiole that is already tightly packed, such as PDF or JPEG. Is that so? Well, I am still disappointed in Retrospect's compression when doing a full backup to a disk back up set. For example, I have a network drive that has 2385 files (158.1MB). The drive contains a large mixture of file types, e.g., ZIP, PDF, txt, htm, doc, RTF, C and others. Yet BOTH times I have done a full backup of the drive, the compression is reported as 0%. The drive is being backed up from the main computer over the net, not as a Client. I expect that 0% actually means "less than 1%". I find it difficult to believe that better compression should not occur for the files on that drive. On the main computer, I have a drive that has been fully backed up twice. In one case, there were 3165 files (2GB), in the other case, 3171 files (2.5GB). Both times 0% compression was reported. Most of the files are of the type that I expect Retrospect is not compressing, e.g., it has all 4 Retrospect catalogs, the ISO 9660 image file for the DR CD, the Office XP PIA files, two MSDN libraries, etc. On this drive, I can believe that effective compression would be low. What are the criteria for determing whther Retrospect would compress a file? Link to comment Share on other sites More sharing options...
Mayoff Posted July 10, 2003 Report Share Posted July 10, 2003 Retrospect does not guess. It uses a compression filter for software compression that we have created that contains files of a known compression types. It is a very long list of pre-compressed file types (like .zip, mp3, jpg etc.). Files matching these types are not compressed with software compression. If you have hardware compression, then we have no control over the compression process. To edit or change the compression filter: Go to Configure. Shift Click on Selectors. Edit the compression selector. Do not change the name of this selector. Link to comment Share on other sites More sharing options...
kaikow Posted February 6, 2006 Author Report Share Posted February 6, 2006 I'm still very disappointed with Retrospect's default compression, at least in version 6.5. Has this improved in version 7? So, I wrote a program to get the didtribution of file types on a driive or path. To see how effective is the compression of a backup program, it is necessary to know how many bytes are actually on the source drives to be backed up, and the distribution of file types. Over the years, I've needlessly wasted time starting My Computer and copying the info into an Excel spreadsheet to determine disk use. I finally got around to writing a quickie program to get the info. See http://www.standards.com/index.html?GetDiskSpaceUsed Also, see http://www.standards.com/index.html?GetFileTypeDistribution Periodically, I may post updates to the programs described in this thread. When I do, I will try to remember to modify the relevant HTML page to update the program's version number, I will no longer announce such things here. So, if you encounter a problem, please first try the latest version before reporting the problem. Link to comment Share on other sites More sharing options...
waltr Posted February 6, 2006 Report Share Posted February 6, 2006 hi howard, cool program. might i also suggest to those looking for something like this these two free alternatives: http://www.werkema.com/software/spacemonger.html http://windirstat.sourceforge.net/ Link to comment Share on other sites More sharing options...
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