Chris Howells schrieb: > Hi Ralf, > > Ralf Gross wrote: > > 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 > > I am very interested in this too. So far I have got even less than that > on a volume, though I know that the data I am currently testing with is > not *that* compressible.
I could test the LTO-4 drive with data from an other server. With LTO-3 I get 2:1 compression for this data. But these files are a completely different kind of data, mostly office documents. The data I'm backing up to LTO-4 is mainly video data (hdf files) which might be not that compressible. > Tomorrow I intend to do some benchmarking of different block sizes to > see what effect they have on performance and compression. Ah, I remember the thread a few weeks ago. > > 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. > > My drive is using 0x46: > > [EMAIL PROTECTED]:~# mt -f /dev/st0 status > SCSI 2 tape drive: > File number=51, block number=0, partition=0. > Tape block size 0 bytes. Density code 0x46 (no translation). > Soft error count since last status=0 > General status bits on (81010000): > EOF ONLINE IM_REP_EN > > Is that what yours is using too? I'm still running the first backup, thus I can't access the drive with mt. 'mt densities' doesn't show any LTO values at all on debian. > I'm using mt-st by the way, it seems more featureful than GNU mt, which > was the one that was already installed on my Ubuntu box. I use the mt-st that comes with debian. Ralf ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
