dtilbor Posted September 13, 2003 Report Posted September 13, 2003 I'm backing up to internal hard disks and for each script have selected the option "Data Compression in Software". When I look at the Operations Log, sometimes Retrospect will use compression for a source, sometimes it shows 0% compression. There is no hardware compression set on the hard disks. Retrospect 6.5 on XP Home. Thanks!
Scott(BAH) Posted September 15, 2003 Report Posted September 15, 2003 Dave, I'm not a Retrospect Expert, but I would assume if you see that message the the files that you backed up were not able to be compressed. Hence the 0% compression. The files could have been graphic files or could have already been compressed (.ZIP,.TAR, etc...) -Scott
natew Posted September 16, 2003 Report Posted September 16, 2003 Hi Scott is correct. Retrospect does not compress files that are already compressed. Nate
dtilbor Posted October 4, 2003 Author Report Posted October 4, 2003 Sorry, I have been away . . . thanks for the replies. No, the instances I've noticed, compression is not applied for an entire session, and there is no chance that all the files are already compressed. Dave
kaikow Posted October 4, 2003 Report Posted October 4, 2003 Quote: Scott(BAH) said: Dave, I'm not a Retrospect Expert, but I would assume if you see that message the the files that you backed up were not able to be compressed. Hence the 0% compression. The files could have been graphic files or could have already been compressed (.ZIP,.TAR, etc...) -Scott My experience has been, at least for a Recyle backup, that Retrospect does not do as good a job at compressing as some other programs. THis is based solely on the percentage figures reported by retrospect and calculating the percent done by BackUp MyPC. Recently, I did a recycle backup with REtrospect and full backup wit BUMP to the same USB drive. Retrospect claimed to have a 13% compression. BUMP was, as I recall, 29%. Backups were run within a couple of hours of each other so, in effect, th esame files were backed up in both cases, However, I do believe that the 0% figure could be misleading, and perhaps, the way Retrospect rounds its numbers could make compression seem worse than it really is. I would suggest that, instead of using percentages, the number of actual bytes in the files and the resultant number of bytes backed up, after compression, be reported. It also may be useful to produce, optionally, a separate log of all files backed up, giving their original size and their compressed size. Perhaps, Retrospect does not compress certain types of files, e.g., PDF, because it is felt that would not be beneficial. I have fould that PDF files can usually be compressed, but not by much. Perhaps, there should be a user option to select which of such types to compress?
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