On 31/01/18 10:14, Ben Laurie wrote: > I also have that on my LTO3 drive.
You should test this using the fill command in btape (which will test with uncompressible data). if the block size is set correctly you're going to achieve very close to the published throughput. Please note that 250MB/s for LTO4 is faster than the uncompressed speed of the tape, but _slow_ for compressible data. Experiments here found the optimum size to be at least 256kB. Mine's set to 1MB. Also note that block size is not the same as the tape drive buffer size. Early drives have around 100MB buffer and LTO4 onwards have at least 600MB buffer. I suspect that's been increased again in LTO8 but haven't got my hands on one to interrogate. Apart from write speed, smaller blocks mean you will write less data per tape due to the ratio of block headers to data, and smaller blocks have a significantly lower restore speed. > > > On 21 December 2017 at 23:08, Dan Langille <d...@langille.org > <mailto:d...@langille.org>> wrote: > > Hello, > > I'm using Bacula 7.4.7 on FreeBSD 11 > > What Bytes/block are you using for your LTO4 tapes? > > I ask because I just noticed: > > ### > Device tape is "LTO_0" (/dev/nsa0) mounted with: > Volume: 000034L4 > Pool: FullsLTO4 > Media type: LTO4 > Slot 38 is loaded in drive 0. > Total Bytes=20,127,937,536 Blocks=312,002 Bytes/block=64,512 > Positioned at File=20 Block=2,003 > ### > > What are you using and why? > > Thank you. > > -- > Dan Langille - BSDCan / PGCon > d...@langille.org <mailto:d...@langille.org> > > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Bacula-users mailing list > Bacula-users@lists.sourceforge.net > <mailto:Bacula-users@lists.sourceforge.net> > https://lists.sourceforge.net/lists/listinfo/bacula-users > <https://lists.sourceforge.net/lists/listinfo/bacula-users> > > > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > > _______________________________________________ > Bacula-users mailing list > Bacula-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bacula-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
