0109de62-5ff2-4ec8-b3d6-e2ef22f90a61 Posted September 21, 2011 Report Share Posted September 21, 2011 Currently we are writing 750GB to LTO4 800 tapes. The transfer rate is 2.1Gb per minute, so about 33Mb per second. Using a different software and utility, we were writing 120Mbs, so 7.2Gbm. I am not writing compressed tapes. What is the optimal settings to use when writing LTO4 tapes to reach 7.2Gbm? Our most recent test using a single 19GB file took 33 minutes to transfer to tape. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted September 22, 2011 Report Share Posted September 22, 2011 Using a different software and utility, we were writing 120Mbs, so 7.2Gbm. Backing up exactly the same set of files? Smaller files takes (a lot) longer time than a few large files (for the same total size in bytes). Maybe the different software transfers the large files first, but Retrospect doesn't? Quote Link to comment Share on other sites More sharing options...
prl Posted September 22, 2011 Report Share Posted September 22, 2011 (edited) Backing up exactly the same set of files? Smaller files takes (a lot) longer time than a few large files (for the same total size in bytes). Maybe the different software transfers the large files first, but Retrospect doesn't? The OP said "a single 19GB file took 33 minutes to transfer to tape". That's less than 0.6GB/min (and < 10 MB/sec). And it's a fairly big file Edited September 22, 2011 by prl Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted September 22, 2011 Report Share Posted September 22, 2011 The OP said "a single 19GB file took 33 minutes to transfer to tape". That's less than 0.6GB/min (and < 10 MB/sec). And it's a fairly big file Right, but does the 33 minutes include scanning a disk with a gazillion files and then matching against which files are already backed up? Quote Link to comment Share on other sites More sharing options...
prl Posted September 22, 2011 Report Share Posted September 22, 2011 Right, but does the 33 minutes include scanning a disk with a gazillion files and then matching against which files are already backed up? Not how I'd do a test like that, but I guess it's conceivable. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted September 22, 2011 Report Share Posted September 22, 2011 Not how I'd do a test like that, but I guess it's conceivable. Right, we don't know anything about the tests performed and what is actually included in the times mentioned in the original post. Quote Link to comment Share on other sites More sharing options...
0109de62-5ff2-4ec8-b3d6-e2ef22f90a61 Posted September 22, 2011 Author Report Share Posted September 22, 2011 Sorry if I didn't post enough info. I'm a complete newbie when it comes to this. The hard drive was empty except for that one file. It was from an internal hard drive. I did not have the "do not backup dup files" turned on. These are all media files between 20min long and 2hr long, largest file is just over 25Gb. Please let me know if there's anything I can post here that can help give you an idea of what I can do, or what I shouldn't be doing. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted September 22, 2011 Report Share Posted September 22, 2011 What is your destination? An empty Media set? Or a media set with a gazillion files already in it? The "different software" you mention in your first post, what is that? Does it read the same file from the same hard drive? Or is it a test program for the tape drive that generates a stream of data in RAM, avoiding the hard disk bottleneck? Quote Link to comment Share on other sites More sharing options...
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