Hi, I'm testing our new changer which is equipped with 2 LTO-4 drives. What should I expect from LTO's hw compression? I've seen LTO-3 tapes with 800+ GB data. Here are the volbytes number I got with LTO-4 so far.
volbytes: 1,164,080,268,288 1,138,440,038,400 1,180,908,417,024 This is a compression ratio of 1,45:1. I know that these numbers are highly dependent on the kind of data that is backed up. The data I'm currently backing up is mainly made up of large hdf files. # du -sh * 1,4G 16bit_chan0.hdf 0 16bit_chan0.hdf_pdetTrigger.log 325M 8bit_chan0.hdf 201M 8bit_chan1.hdf # bzip2 * # du -sh * 447M 16bit_chan0.hdf.bz2 4,0K 16bit_chan0.hdf_pdetTrigger.log.bz2 219M 8bit_chan0.hdf.bz2 652K 8bit_chan1.hdf.bz2 So bzip2 seems to be able to compress the data far better (3,4:1), but the drive has to do it in "real time", thus is might be slower, although compression is implemented in hardware. I'm just wondering if I have to set a special density code with mt (which I don't know at the moment)? LTO-3's code was 0x44 if I remember correctly, but I *think* the default shoulb be ok. I couldn't find any density code for LTO-4 with google. Ralf ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
