Cejka Rudolf wrote (2017/06/05): > Cejka Rudolf wrote (2017/06/02): > > Ivan Adzhubey wrote (2017/06/01): > > > b) What is the effect of MaximumFileSize option and what would be its > > > optimal > > > value for my IBM LTO-5 SAS drives? I have used 8GB value found in one of > > > the > > > list posts, while the documentation suggests 2GB for LTO-4. But even set > > > at > > > 8GB this would create lots of EOF marks on a 1.5TB tape, do we really > > > need so > > > many? > > > > Hi, I do use 16 GB. Every EOF mark means around 3 seconds delay. So if you > > have > > over 200 files on the tape using 8 GB, it is around 10 minutes extra per > > tape. > > Hi, small fix. It seems that it is even around 5-6 seconds delay resulting in > extra 20 minutes per tape. And worse, I'm afraid that the tape drive do not > stop nor slowdown tape movement, which would mean over 10 % of the tape lost > because of filemarks. Hope that I'm wrong.
Hi, I finally have done and finished real testing with Maximum File Size option. Tested on LTO-6 drive with LTO-5 tape, so the results are relevant for LTO-5, used btape utility and fill s (simplified) command. Fortunately, I has negligible impact on tape capacity, but unfortunately, I has really dramatical impact on overall write speed and you have to count not just 5-6 seconds, but better 8-10 seconds per file. I also added time to read one file at 140 MB/s, which is important for seeking during restores. File Simplified Simplified Bytes Files Rough time to size fill time fill rate written written read one file 1 GB 6:44:18 61.8 MB/s 1498688192512 1499 00:00:07 2 GB 4:51:30 85.7 MB/s 1498737278976 750 00:00:14 4 GB 3:54:57 106.3 MB/s 1498762641408 375 00:00:29 8 GB 3:24:22 122.2 MB/s 1499224932352 188 00:00:57 16 GB 3:11:09 130.7 MB/s 1499456405504 94 00:01:54 32 GB 3:04:35 135.4 MB/s 1499690303488 47 00:03:49 64 GB 3:01:17 137.8 MB/s 1499574960128 24 00:07:37 128 GB 2:59:37 139.1 MB/s 1499603664896 12 00:15:14 And it seems that the results are perfectly reproducible. Three successive tests with 16 GB file size have had exactly the same fill time 3:11:09! Tests were done by mistake, when I wondered how it is possible that the time stays exactly the same :o) Regards. -- Rudolf Cejka <cejkar at fit.vutbr.cz> http://www.fit.vutbr.cz/~cejkar Brno University of Technology, Faculty of Information Technology Bozetechova 2, 612 66 Brno, Czech Republic ------------------------------------------------------------------------------ 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
